https://www.therespiratorysystem.com/glossary/alveolar-ducts-and-sacs/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--alveolar-ducts-and-sacs/hero-illustration.webpIllustration of an alveolar duct ending in a cluster of grape-like air sacs wrapped in thin capillarieshttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--alveolar-ducts-and-sacs/hero.webpBranching diagram from terminal bronchiole to respiratory bronchiole, alveolar duct, alveolar sac and alveolushttps://www.therespiratorysystem.com/wp-content/uploads/2017/06/Alveoli.jpgLabeled illustration of a bronchiole ending in an alveolar duct and a grape-like alveolar sac, with pores of Kohn and pulmonary capillarieshttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--alveolar-ducts-and-sacs/duct-vs-sac.webpComparison chart of an alveolar duct and an alveolar sac: shape, airway generation, smooth muscle, air movement and gas exchangehttps://www.therespiratorysystem.com/assets/img/ai/glossary--alveolar-ducts-and-sacs/lung-tissue-sponge.webpIllustration of a slice of lung tissue like a pink sponge full of tiny air spaces with a small airway running through ithttps://www.therespiratorysystem.com/assets/img/ai/glossary--alveolar-ducts-and-sacs/soap-bubbles-cluster.webpIllustration of a child blowing a cluster of soap bubbles that cling together and share thin walls https://www.therespiratorysystem.com/glossary/alveolar-macrophages/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--alveolar-macrophages/hero-illustration.webpIllustration of a large macrophage inside an alveolus engulfing dust particles and bacteriahttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--alveolar-macrophages/hero.webpFive-step diagram of how an alveolar macrophage finds, engulfs, digests and carries away an inhaled particlehttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--alveolar-macrophages/jobs-of-alveolar-macrophages.webpCircular diagram of the six main jobs of an alveolar macrophage, from engulfing particles to calming inflammationhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--alveolar-macrophages/alveolar-vs-interstitial-macrophages.webpComparison chart of alveolar macrophages in the air spaces and interstitial macrophages in the alveolar wallshttps://www.therespiratorysystem.com/assets/img/ai/glossary--alveolar-macrophages/city-air-commuter.webpIllustration of a commuter walking along a busy city street in hazy air with faint floating dust https://www.therespiratorysystem.com/alveoli/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/alveoli/hero-illustration.webpIllustration of a cluster of grape-like alveoli wrapped in a fine net of red and blue capillaries at the end of a small airwayhttps://www.therespiratorysystem.com/wp-content/uploads/2017/06/Alveoli.jpgLabeled diagram of alveoli showing a bronchiole, alveolar duct, alveolar sac, pores of Kohn, pulmonary arteriole, venule and capillarieshttps://www.therespiratorysystem.com/wp-content/uploads/2017/06/Labeled-Diagram-of-Alveoli-Gas-Exchange.jpgDiagram of gas exchange within an alveolus: oxygen diffuses into a capillary red blood cell while carbon dioxide diffuses into the air spacehttps://www.therespiratorysystem.com/assets/img/ai/alveoli/lung-tissue-honeycomb.webpIllustration of a cube of lung tissue cut open to show hundreds of tiny thin-walled alveoli packed like a spongehttps://www.therespiratorysystem.com/assets/img/ai/alveoli/alveolar-macrophage.webpIllustration of an alveolar macrophage on the inner wall of an alveolus engulfing a tiny dust particle https://www.therespiratorysystem.com/glossary/bohr-effect/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--bohr-effect/hero-illustration.webpIllustration of a hemoglobin molecule with four coiled subunits and a few small blue oxygen molecules attachedhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--bohr-effect/hero.webpCycle diagram of the Bohr effect: CO2 and acid from tissues make hemoglobin release oxygen, and CO2 loss in the lungs helps it load oxygenhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--bohr-effect/inside-the-red-blood-cell.webpFive-step diagram of the Bohr effect inside a red blood cell, from carbon dioxide entry to hemoglobin releasing oxygenhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--bohr-effect/bohr-vs-haldane.webpComparison chart of the Bohr effect and the Haldane effect: trigger, what changes, where each helps and which curve shiftshttps://www.therespiratorysystem.com/assets/img/ai/glossary--bohr-effect/sprinter-working-muscles.webpIllustration of a sprinter running at full speed on a track https://www.therespiratorysystem.com/bronchi/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/bronchi/hero-illustration.webpIllustration of the trachea dividing into the right and left main bronchi, with cartilage rings and branches entering the lungshttps://www.therespiratorysystem.com/wp-content/uploads/2017/05/Bronchi.jpgLabeled diagram of the bronchi showing the trachea, carina, right and left primary bronchi, lobar and segmental bronchi inside the lungshttps://www.therespiratorysystem.com/wp-content/uploads/2017/05/Bronchus-Anatomy-Diagram.jpgDiagram of a bronchus wall showing cartilage plates, smooth muscle, mucus lining, ciliated lining, blood vessels and the bronchial lumenhttps://www.therespiratorysystem.com/assets/img/ai/bronchi/carina-view.webpIllustration of the inside of the trachea looking down to the ridge where it divides into the right and left main bronchihttps://www.therespiratorysystem.com/assets/img/ai/bronchi/bronchial-cilia.webpIllustration of cilia and mucus on the lining of a bronchus carrying a dust particle along the surface https://www.therespiratorysystem.com/bronchi-vs-bronchioles/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/bronchi-vs-bronchioles/hero-illustration.webpIllustration of the branching bronchial tree inside transparent lungs, from the large bronchi down to the fine bronchioleshttps://www.therespiratorysystem.com/assets/img/diagrams/bronchi-vs-bronchioles/hero.webpComparison chart of bronchi and bronchioles: size, cartilage, glands, lining, special cells, support and gas exchangehttps://www.therespiratorysystem.com/wp-content/uploads/2017/05/Bronchi.jpgLabeled diagram of the bronchi and bronchioles in both lungs, from the main bronchi to segmental bronchi and small bronchioleshttps://www.therespiratorysystem.com/assets/img/diagrams/bronchi-vs-bronchioles/where-bronchi-become-bronchioles.webpBranching diagram from the trachea and main bronchi to respiratory bronchioles, marking where bronchi become bronchioleshttps://www.therespiratorysystem.com/assets/img/ai/bronchi-vs-bronchioles/bronchus-wall-close-up.webpIllustration of a wide bronchus with cartilage plates beside a narrow bronchiole with a thin smooth wall, both cut openhttps://www.therespiratorysystem.com/assets/img/ai/bronchi-vs-bronchioles/bronchiole-to-alveoli.webpIllustration of a fine bronchiole ending in clusters of tiny air sacs wrapped in red and blue capillaries https://www.therespiratorysystem.com/bronchial-tree/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/bronchial-tree/hero-illustration.webpIllustration of the lungs seen from the front with the trachea and the branching bronchial tree glowing inside translucent pink lungshttps://www.therespiratorysystem.com/assets/img/diagrams/bronchial-tree/hero.webpBranching diagram of the bronchial tree from the trachea through main, lobar and segmental bronchi and bronchioles to the alveolihttps://www.therespiratorysystem.com/assets/img/diagrams/bronchial-tree/right-vs-left.webpComparison chart of the right and left bronchial trees: main bronchus shape, number of lobar and segmental bronchi and nearby vesselshttps://www.therespiratorysystem.com/assets/img/diagrams/bronchial-tree/what-the-tree-does.webpSix-step diagram of the functions of the bronchial tree: conducting, distributing, warming, cleaning, adjusting flow and starting gas exchangehttps://www.therespiratorysystem.com/assets/img/ai/bronchial-tree/airway-cutaway.webpIllustration of a branching airway cut open to show its pink lining, cartilage plates in the wide tube and a thinner wall in the narrow branch https://www.therespiratorysystem.com/bronchioles/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/bronchioles/hero-illustration.webpIllustration of the inside of a bronchiole, a narrow round airway lined with pink tissue opening into tiny alveolihttps://www.therespiratorysystem.com/wp-content/uploads/2017/04/Bronchioles.jpgLabeled diagram of the bronchioles showing a lobular bronchiole, terminal and respiratory bronchioles, alveolar ducts, alveolar sacs and capillarieshttps://www.therespiratorysystem.com/assets/img/ai/bronchioles/bronchiole-tree.webpIllustration of semi-transparent human lungs showing bronchi branching into fine bronchioles that end in clusters of alveolihttps://www.therespiratorysystem.com/assets/img/ai/bronchioles/bronchiole-open-vs-narrow.webpIllustration comparing a wide open bronchiole with relaxed smooth muscle and a narrowed bronchiole with tightened smooth muscle https://www.therespiratorysystem.com/bronchopulmonary-segments/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/bronchopulmonary-segments/hero-illustration.webpIllustration of both lungs in front view with each lung segment tinted a different soft pastel colorhttps://www.therespiratorysystem.com/assets/img/diagrams/bronchopulmonary-segments/hero.webpComparison diagram of the bronchopulmonary segments of the right lung and the left lung, listed lobe by lobehttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Picture-of-Lung-Segments-Anatomy.jpgColor-coded diagram of the bronchopulmonary segments of both lungs in anterior, posterior and medial viewshttps://www.therespiratorysystem.com/assets/img/diagrams/bronchopulmonary-segments/airway-levels.webpBranching diagram showing where the segmental bronchi sit in the airway tree, from the trachea down to the alveolihttps://www.therespiratorysystem.com/assets/img/diagrams/bronchopulmonary-segments/center-vs-border.webpComparison chart of what lies at the center of a bronchopulmonary segment and at the border between two segmentshttps://www.therespiratorysystem.com/assets/img/ai/bronchopulmonary-segments/single-segment-unit.webpIllustration of one cone-shaped lung segment with its own bronchus and artery running down the middlehttps://www.therespiratorysystem.com/assets/img/ai/bronchopulmonary-segments/lung-model-classroom.webpIllustration of a classroom anatomy model of the lungs with removable colored segments on a desk https://www.therespiratorysystem.com/carbon-dioxide-transport/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/carbon-dioxide-transport/hero-illustration.webpIllustration of red blood cells passing single file through a capillary beside tissue cells that release carbon dioxide into the bloodhttps://www.therespiratorysystem.com/assets/img/diagrams/carbon-dioxide-transport/hero.webpSix-step diagram of carbon dioxide transport: CO2 enters red blood cells, carbonic anhydrase forms bicarbonate, and the chloride shift followshttps://www.therespiratorysystem.com/assets/img/diagrams/carbon-dioxide-transport/three-forms.webpBar diagram comparing the three forms of carbon dioxide transport: bicarbonate largest, carbamino compounds middle, dissolved gas smallesthttps://www.therespiratorysystem.com/assets/img/diagrams/carbon-dioxide-transport/tissues-vs-lungs.webpComparison chart of carbon dioxide transport in the tissues and in the lungs, showing the reactions running in opposite directionshttps://www.therespiratorysystem.com/assets/img/ai/carbon-dioxide-transport/exhaled-breath.webpIllustration of a person in a scarf breathing out a cloud of visible breath on a cold morning https://www.therespiratorysystem.com/glossary/cardiac-notch/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--cardiac-notch/hero-illustration.webpIllustration of the heart nestled into the curved front edge of the left lung, seen from the fronthttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--cardiac-notch/hero.webpComparison chart of the cardiac notch and the lingula of the left lung: location, lobe, structure and right lung counterparthttps://www.therespiratorysystem.com/wp-content/uploads/2017/11/Lung-Lobes.jpgLabeled diagram of the right and left lungs showing the lobes, fissures and the cardiac notch in the left lunghttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--cardiac-notch/anterior-border.webpFive-step diagram tracing the anterior border of the left lung from the apex past the cardiac notch to the lingulahttps://www.therespiratorysystem.com/assets/img/ai/glossary--cardiac-notch/left-lung-lateral.webpIllustration of an isolated left lung from the front, with a curved scoop on its inner edge and a small tongue of lung below ithttps://www.therespiratorysystem.com/assets/img/ai/glossary--cardiac-notch/stethoscope-check.webpIllustration of a clinician holding a stethoscope to the chest of a calm, clothed adult in a bright clinic https://www.therespiratorysystem.com/glossary/carina/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--carina/hero-illustration.webpIllustration of the trachea dividing into the right and left main bronchi with the lungs faintly visible behindhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--carina/hero.webpBranching diagram showing the trachea dividing at the carina into the right and left main bronchi, then lobar and segmental bronchihttps://www.therespiratorysystem.com/wp-content/uploads/2017/03/Carina-of-Trachea.jpgLabeled illustration of the tracheal bifurcation, with the carina ridge seen inside the trachea between the right and left bronchushttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--carina/carina-cough-trigger.webpFive-step diagram of how irritation of the carina triggers the cough reflex through the vagus nerve and brainstemhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--carina/carina-wall.webpLayer diagram of the carina wall: respiratory epithelium, lamina propria and submucosa, hyaline cartilage and adventitiahttps://www.therespiratorysystem.com/assets/img/ai/glossary--carina/inside-the-carina.webpIllustration of the lower windpipe cut open to show the keel-shaped ridge that splits the airway in twohttps://www.therespiratorysystem.com/assets/img/ai/glossary--carina/carina-in-chest.webpIllustration of the windpipe splitting into two bronchi between the lungs https://www.therespiratorysystem.com/cilia-and-mucus/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/cilia-and-mucus/hero-illustration.webpIllustration of a microscopic forest of cilia in the airway carrying a thin layer of mucus with trapped dust particleshttps://www.therespiratorysystem.com/assets/img/diagrams/cilia-and-mucus/hero.webpSix-step diagram of the mucociliary escalator: a particle is trapped in mucus, cilia move the mucus up the airways and it is swallowedhttps://www.therespiratorysystem.com/assets/img/diagrams/cilia-and-mucus/airway-surface-layers.webpLayer diagram of the airway surface: mucus gel layer, periciliary layer, ciliated epithelium, basement membrane and glandshttps://www.therespiratorysystem.com/assets/img/diagrams/cilia-and-mucus/cilia-vs-mucus.webpComparison chart of cilia and mucus in the airways: what each is, which cells make it, its job, location and what goes wronghttps://www.therespiratorysystem.com/assets/img/ai/cilia-and-mucus/inside-the-trachea.webpIllustration looking up inside the windpipe, whose moist pink wall is coated with a thin film of mucus https://www.therespiratorysystem.com/conducting-zone-vs-respiratory-zone/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/conducting-zone-vs-respiratory-zone/hero-illustration.webpIllustration of a lung cut open, with wide branching airways near the center and fine spongy air-sac tissue near the outer edgehttps://www.therespiratorysystem.com/assets/img/diagrams/conducting-zone-vs-respiratory-zone/hero.webpAirway tree diagram: conducting zone from trachea to terminal bronchioles, respiratory zone from respiratory bronchioles to alveolihttps://www.therespiratorysystem.com/assets/img/diagrams/conducting-zone-vs-respiratory-zone/zones-compared.webpComparison chart of the conducting zone and the respiratory zone: job, start, end, gas exchange, lining, cleaning and air movementhttps://www.therespiratorysystem.com/assets/img/diagrams/conducting-zone-vs-respiratory-zone/one-breath.webpSix-step diagram of one breath moving through the conducting zone into the respiratory zone and back outhttps://www.therespiratorysystem.com/assets/img/ai/conducting-zone-vs-respiratory-zone/airway-lining.webpIllustration of the ciliated, mucus-covered lining of a large airway with goblet cells and cartilage in the wall https://www.therespiratorysystem.com/control-of-breathing/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/control-of-breathing/hero-illustration.webpIllustration of the brainstem glowing at the base of the brain with a nerve running down the neck to the diaphragm and lungshttps://www.therespiratorysystem.com/assets/img/diagrams/control-of-breathing/hero.webpFeedback loop diagram of breathing control: sensors, brainstem respiratory centers, motor nerves, breathing muscles and blood gaseshttps://www.therespiratorysystem.com/assets/img/diagrams/control-of-breathing/carbon-dioxide-response.webpSix-step diagram showing how rising carbon dioxide acidifies brain fluid, triggers chemoreceptors and increases ventilationhttps://www.therespiratorysystem.com/assets/img/diagrams/control-of-breathing/automatic-vs-voluntary.webpComparison chart of automatic brainstem control of breathing and voluntary cortical control of breathinghttps://www.therespiratorysystem.com/assets/img/ai/control-of-breathing/sleeping-person.webpIllustration of a person sleeping peacefully on their side in a moonlit bedroom https://www.therespiratorysystem.com/glossary/dead-space/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--dead-space/hero-illustration.webpIllustration of a head and chest in side cutaway with the airways from nose to main bronchi glowing as a pale blue air-filled tubehttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--dead-space/hero.webpBranching diagram of the airways showing anatomical dead space from the nose to the terminal bronchioles and the gas exchange zone beyondhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--dead-space/anatomical-vs-physiological.webpComparison chart of anatomical and physiological dead space: what each counts, where, typical size, measurement and causes of increasehttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--dead-space/breathing-patterns.webpBar chart comparing alveolar ventilation with deep slow, normal and shallow fast breathing at the same minute ventilationhttps://www.therespiratorysystem.com/assets/img/ai/glossary--dead-space/snorkel-dead-space.webpIllustration of a snorkel and diving mask lying on a sunny beach at the water's edge https://www.therespiratorysystem.com/diaphragm/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/diaphragm/hero-illustration.webpIllustration of the dome-shaped diaphragm seen from below, with muscle fibers fanning out from a central tendonhttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Diaphragm.jpgDiaphragm seen from above with central tendon, crura, caval and esophageal openings, aorta, phrenic nerves and lumbar vertebrae labeledhttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Diaphragm-Muscle-Location-Picture.jpgFront view of the rib cage showing the diaphragm muscle with its right and left domes, central tendon, esophageal and aortic openingshttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Diaphragm-Function-in-Breathing.jpgSide-by-side diagram of inhalation and exhalation showing the diaphragm flattening and relaxing as the chest and lungs expand and shrinkhttps://www.therespiratorysystem.com/assets/img/ai/diaphragm/diaphragm-openings.webpIllustration of the dome-shaped diaphragm with three tubes passing through openings in ithttps://www.therespiratorysystem.com/assets/img/ai/diaphragm/belly-breathing.webpIllustration of a relaxed person lying on a yoga mat with one hand on the chest and one on the belly during slow diaphragmatic breathing https://www.therespiratorysystem.com/epiglottis/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/epiglottis/hero-illustration.webpIllustration of the throat structures from the side showing the leaf-shaped epiglottis above the larynxhttps://www.therespiratorysystem.com/wp-content/uploads/2016/12/Epiglottis.jpgSide view of the head and neck showing the epiglottis behind the tongue, above the larynx, with the trachea and esophagus belowhttps://www.therespiratorysystem.com/wp-content/uploads/2016/12/Epiglottis-Anatomy-Diagram.jpgAnterior and posterior views of the larynx showing the epiglottis above the hyoid bone and thyroid cartilage, with the tracheal cartilages belowhttps://www.therespiratorysystem.com/assets/img/ai/epiglottis/drinking-water.webpIllustration of a person at a kitchen table swallowing a sip of water from a glasshttps://www.therespiratorysystem.com/assets/img/ai/epiglottis/larynx-from-above.webpIllustration of the larynx seen from above, showing the epiglottis at the front and the vocal folds forming the glottis https://www.therespiratorysystem.com/ethmoid-sinus/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/ethmoid-sinus/hero-illustration.webpIllustration of a translucent skull in front view with the honeycomb of ethmoid air cells between the eye socketshttps://www.therespiratorysystem.com/assets/img/diagrams/ethmoid-sinus/hero.webpComparison chart of the anterior and posterior ethmoid air cells: position, size, drainage, named cells, nerves, arteries and neighborshttps://www.therespiratorysystem.com/assets/img/diagrams/ethmoid-sinus/eye-to-nose.webpLayer diagram from the orbit to the nasal cavity: eye socket, lamina papyracea, ethmoid air cells, medial wall with conchae, nasal cavityhttps://www.therespiratorysystem.com/assets/img/diagrams/ethmoid-sinus/keros-classification.webpBar diagram of the Keros classification showing a shallow type I, medium type II and deep type III olfactory fossahttps://www.therespiratorysystem.com/assets/img/ai/ethmoid-sinus/child-skull-sinuses.webpIllustration of a child's translucent skull with a few small developing ethmoid air cells near the nose https://www.therespiratorysystem.com/external-and-internal-respiration/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/external-and-internal-respiration/hero-illustration.webpIllustration of a cluster of alveoli wrapped in a fine network of red and blue capillarieshttps://www.therespiratorysystem.com/assets/img/diagrams/external-and-internal-respiration/hero.webpComparison chart of external respiration in the lungs and internal respiration in the tissues, with gas directions and oxygen pressureshttps://www.therespiratorysystem.com/assets/img/diagrams/external-and-internal-respiration/four-processes.webpCycle diagram linking pulmonary ventilation, external respiration, gas transport, internal respiration and cellular respirationhttps://www.therespiratorysystem.com/assets/img/diagrams/external-and-internal-respiration/internal-respiration-steps.webpSix-step diagram of internal respiration from arterial blood arriving in a tissue to oxygen-poor venous blood returning to the hearthttps://www.therespiratorysystem.com/assets/img/ai/external-and-internal-respiration/capillary-to-muscle-cell.webpIllustration of red blood cells in a thin capillary releasing oxygen to a neighboring muscle cell https://www.therespiratorysystem.com/frontal-sinus/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/frontal-sinus/hero-illustration.webpIllustration of a skull in front view with the air-filled frontal sinuses glowing blue above the eye socketshttps://www.therespiratorysystem.com/assets/img/diagrams/frontal-sinus/hero.webpLayer diagram from the forehead inward: skin and muscle, anterior table, frontal sinus air space, posterior table, dura and frontal lobehttps://www.therespiratorysystem.com/assets/img/diagrams/frontal-sinus/frontal-sinus-drainage.webpSix-step diagram of frontal sinus drainage: mucus moves through the funnel-shaped floor, ostium and frontal recess into the middle meatushttps://www.therespiratorysystem.com/assets/img/ai/frontal-sinus/ct-scan-room.webpIllustration of a calm adult lying on a CT scanner table with the head entering the scanner ring https://www.therespiratorysystem.com/respiratory-system-functions/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-functions/hero-illustration.webpIllustration of a translucent human torso showing the nose, windpipe, bronchi and both lungshttps://www.therespiratorysystem.com/wp-content/uploads/2017/10/Trace-the-Airflow-Pathway-Through-the-Respiratory-System.jpgDiagram of the pathway of air through the respiratory system, from the nostrils and nasal cavity down the trachea and bronchi to the alveolihttps://www.therespiratorysystem.com/wp-content/uploads/2017/10/Respiratory-System-Functions.jpgLabeled chart of respiratory system functions naming the job of the nasal cavity, pharynx, larynx, trachea, bronchi, alveoli and diaphragmhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-functions/smelling-fresh-bread.webpIllustration of a person in a bakery holding a fresh loaf near the face and breathing in its smellhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-functions/swimmer-breathing.webpIllustration of a swimmer turning the head to take a breath in the middle of freestyle in a pool lane https://www.therespiratorysystem.com/gas-exchange/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/gas-exchange/hero-illustration.webpIllustration of a hiker in a mountain meadow at sunrise taking a deep breath of fresh airhttps://www.therespiratorysystem.com/assets/img/diagrams/gas-exchange/hero.webpDiagram of gas exchange between an alveolus and a pulmonary capillary: oxygen diffuses into the blood and carbon dioxide diffuses outhttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Gas-Exchange-in-the-Lungs-Image.jpgLabeled illustration of alveoli and their capillaries, with a close-up of oxygen entering red blood cells and carbon dioxide leaving themhttps://www.therespiratorysystem.com/assets/img/diagrams/gas-exchange/oxygen-pathway.webpSix-step diagram of the path of an oxygen molecule from an alveolus across the respiratory membrane to hemoglobin in a red blood cellhttps://www.therespiratorysystem.com/assets/img/diagrams/gas-exchange/lungs-vs-tissues.webpComparison chart of gas exchange in the lungs (external respiration) and in the tissues (internal respiration)https://www.therespiratorysystem.com/assets/img/ai/gas-exchange/alveolus-capillary-macro.webpIllustration of oxygen molecules crossing a thin alveolar wall into a red blood cell while carbon dioxide drifts outhttps://www.therespiratorysystem.com/assets/img/ai/gas-exchange/fish-gill.webpIllustration of the bright red feathery gill filaments of a fish in clear water https://www.therespiratorysystem.com/glossary/glottis/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--glottis/hero-illustration.webpIllustration of a cutaway of the neck showing the larynx, the vocal folds in the middle of the airway and the windpipe belowhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--glottis/hero.webpComparison chart of the open glottis during breathing and the closed glottis during speech, coughing and swallowinghttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--glottis/levels-of-the-larynx.webpLayered diagram of the levels of the larynx from the laryngeal inlet and supraglottis to the glottis, subglottis and tracheahttps://www.therespiratorysystem.com/assets/img/ai/glossary--glottis/dog-barking.webpIllustration of a brown dog barking in a green meadow with its mouth open https://www.therespiratorysystem.com/epiglottis-vs-glottis/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/epiglottis-vs-glottis/hero-illustration.webpIllustration of the larynx seen from above, with the leaf-shaped epiglottis at the front and the V-shaped opening between the vocal foldshttps://www.therespiratorysystem.com/assets/img/diagrams/epiglottis-vs-glottis/hero.webpComparison chart of the epiglottis and the glottis: what each is, position in the larynx, tissue, movement and main jobhttps://www.therespiratorysystem.com/assets/img/diagrams/epiglottis-vs-glottis/larynx-top-to-bottom.webpLayered diagram of the larynx from top to bottom: epiglottis, laryngeal inlet, vestibule and vestibular folds, glottis and subglottishttps://www.therespiratorysystem.com/assets/img/diagrams/epiglottis-vs-glottis/swallowing-closure.webpSix-step diagram of airway closure during swallowing: glottis, vestibular folds, laryngeal elevation and epiglottishttps://www.therespiratorysystem.com/assets/img/ai/epiglottis-vs-glottis/drinking-water.webpIllustration of a person drinking a glass of water at a table, side view, mid-swallow https://www.therespiratorysystem.com/hilum-of-lung/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/hilum-of-lung/hero-illustration.webpIllustration of the inner surface of the right lung showing the bronchus, artery and veins entering at the hilumhttps://www.therespiratorysystem.com/assets/img/diagrams/hilum-of-lung/hero.webpComparison diagram of the right and left lung hila showing the position of the bronchus, pulmonary artery, pulmonary veins and nearby structureshttps://www.therespiratorysystem.com/assets/img/diagrams/hilum-of-lung/front-to-back.webpLayered diagram of the lung root showing pulmonary veins in front, pulmonary artery in the middle and bronchus at the backhttps://www.therespiratorysystem.com/assets/img/diagrams/hilum-of-lung/hilum-vs-root.webpComparison chart explaining the difference between the hilum of the lung and the root of the lunghttps://www.therespiratorysystem.com/assets/img/ai/hilum-of-lung/radiology-chest-xray.webpIllustration of a doctor in a reading room viewing a chest X-ray on a large monitor https://www.therespiratorysystem.com/respiratory-and-circulatory-system/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-and-circulatory-system/hero-illustration.webpIllustration of the heart between the two lungs, joined by the pulmonary arteries and veinshttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-and-circulatory-system/hero.webpCycle diagram of how the respiratory and circulatory systems work together: lungs, left heart, body tissues and right heart in one loophttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-and-circulatory-system/respiratory-vs-circulatory-compare.webpComparison chart of the respiratory system and the circulatory system: job, organs, what flows, pump, exchange site and controlhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-and-circulatory-system/oxygen-journey.webpSix-step diagram of an oxygen molecule traveling from inhaled air through the lungs, blood and heart to a muscle cellhttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Gas-Exchange-in-the-Lungs-Image.jpgIllustration of alveoli wrapped in pulmonary capillaries, with oxygen entering and carbon dioxide leaving red blood cellshttps://www.therespiratorysystem.com/assets/img/ai/respiratory-and-circulatory-system/airway-vessel-cast.webpIllustration of a resin cast of the lungs with white airways, blue arteries and red veins branching side by side like treeshttps://www.therespiratorysystem.com/assets/img/ai/respiratory-and-circulatory-system/pulse-after-jog.webpIllustration of a jogger on a park path pausing to check their pulse at the wrist https://www.therespiratorysystem.com/how-the-voice-is-produced/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/how-the-voice-is-produced/hero-illustration.webpIllustration of a singer on a softly lit stage holding a long note into a microphonehttps://www.therespiratorysystem.com/assets/img/diagrams/how-the-voice-is-produced/hero.webpSix-step diagram of phonation: breath in, vocal folds close, pressure builds, folds vibrate, air puffs make a tone, the vocal tract shapes ithttps://www.therespiratorysystem.com/assets/img/diagrams/how-the-voice-is-produced/vibration-cycle.webpCycle diagram of one vocal fold vibration: closed, pressure rises, folds open, a puff of air escapes, folds snap shuthttps://www.therespiratorysystem.com/assets/img/diagrams/how-the-voice-is-produced/phonation-vs-resonance.webpComparison chart of phonation and resonance: where each happens, what each controls and which structures are involvedhttps://www.therespiratorysystem.com/assets/img/ai/how-the-voice-is-produced/three-generations.webpIllustration of a child, an adult and an older woman sitting together on a sofa talking and laughing https://www.therespiratorysystem.com/inhalation-and-exhalation/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/inhalation-and-exhalation/hero-illustration.webpIllustration of a person at a misty lakeside at dawn taking a slow deep breath inhttps://www.therespiratorysystem.com/assets/img/diagrams/inhalation-and-exhalation/hero.webpBreathing cycle diagram: the diaphragm contracts and air flows in, then the muscles relax, the lungs recoil and air flows outhttps://www.therespiratorysystem.com/assets/img/diagrams/inhalation-and-exhalation/inhalation-steps.webpSix-step inhalation process diagram from the brain signal and diaphragm contraction to air flowing into the alveolihttps://www.therespiratorysystem.com/assets/img/diagrams/inhalation-and-exhalation/inhalation-vs-exhalation-chart.webpInhalation vs exhalation comparison chart showing the diaphragm, ribs, chest volume, pressure and airflow in each phasehttps://www.therespiratorysystem.com/assets/img/ai/inhalation-and-exhalation/blowing-candles.webpIllustration of a child blowing out the candles on a birthday cake with puffed cheeks https://www.therespiratorysystem.com/laryngeal-cartilages/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/laryngeal-cartilages/hero-illustration.webpIllustration of the larynx from the front showing the shield-shaped thyroid cartilage, the cricoid ring and the hyoid bonehttps://www.therespiratorysystem.com/assets/img/diagrams/laryngeal-cartilages/hero.webpComparison chart of the 3 unpaired and 3 paired laryngeal cartilages: members, number, size, tissue, job and jointshttps://www.therespiratorysystem.com/wp-content/uploads/2016/11/Larynx-Anatomy.jpgAnterior, side and posterior views of the larynx showing the epiglottis, thyroid, cricoid and arytenoid cartilages and the vocal cordshttps://www.therespiratorysystem.com/assets/img/diagrams/laryngeal-cartilages/how-muscles-move-the-cartilages.webpSix-step diagram of how laryngeal muscles move the arytenoid, thyroid and epiglottic cartilages to open, close and tense the vocal cordshttps://www.therespiratorysystem.com/assets/img/ai/laryngeal-cartilages/larynx-from-behind.webpIllustration of the larynx from behind showing the cricoid ring with the two small arytenoid cartilages on tophttps://www.therespiratorysystem.com/assets/img/ai/laryngeal-cartilages/adams-apple-profile.webpIllustration of a man in profile with the Adam's apple visible at the front of the neck https://www.therespiratorysystem.com/laryngopharynx/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/laryngopharynx/hero-illustration.webpIllustration of the throat seen from behind with the back wall opened to show the epiglottis, the larynx entrance and the esophagushttps://www.therespiratorysystem.com/assets/img/diagrams/laryngopharynx/hero.webpStacked diagram of the pharynx showing the nasopharynx, oropharynx and laryngopharynx from top to bottom, ending where the larynx and esophagus splithttps://www.therespiratorysystem.com/assets/img/diagrams/laryngopharynx/swallow-through-the-laryngopharynx.webpSix-step diagram of a swallow through the laryngopharynx, from the larynx rising and the airway sealing to food entering the esophagushttps://www.therespiratorysystem.com/assets/img/diagrams/laryngopharynx/larynx-vs-laryngopharynx.webpComparison chart of the larynx and the laryngopharynx by name, position, what each carries, framework, lining, job and where each leadshttps://www.therespiratorysystem.com/assets/img/ai/laryngopharynx/older-adult-tea.webpIllustration of an elderly man in a cozy living room sipping a cup of tea https://www.therespiratorysystem.com/larynx/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/larynx/hero-illustration.webpIllustration of an isolated larynx with the shield-shaped thyroid cartilage, ring-shaped cricoid cartilage and hyoid bone abovehttps://www.therespiratorysystem.com/wp-content/uploads/2016/11/Larynx-Diagram.jpgSide view of the head and neck showing the larynx with its supraglottis, glottis, vocal cord and subglottis between the epiglottis and tracheahttps://www.therespiratorysystem.com/wp-content/uploads/2016/11/Larynx-Anatomy.jpgAnterior, side and posterior views of the larynx with the epiglottis, hyoid bone, thyroid and cricoid cartilages, vocal cords and tracheal ringshttps://www.therespiratorysystem.com/assets/img/ai/larynx/adams-apple-profile.webpIllustration of the side of an adult neck with the bump of the Adam's apple visible at the fronthttps://www.therespiratorysystem.com/assets/img/ai/larynx/humming-woman.webpIllustration of a woman humming quietly with her eyes closed in a cozy armchair https://www.therespiratorysystem.com/larynx-vs-pharynx/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/larynx-vs-pharynx/hero-illustration.webpIllustration of a head and neck in side cutaway showing the pharynx as a pink tube above the cartilage box of the larynxhttps://www.therespiratorysystem.com/assets/img/diagrams/larynx-vs-pharynx/hero.webpComparison chart of the pharynx (throat) and larynx (voice box): what passes, position, length, structure, parts and jobshttps://www.therespiratorysystem.com/wp-content/uploads/2016/09/Pharynx.jpgLabeled side view of the head and neck showing the nasopharynx, oropharynx and laryngopharynx, with the larynx in front and the esophagus behindhttps://www.therespiratorysystem.com/assets/img/diagrams/larynx-vs-pharynx/front-to-back.webpLayered diagram from the front to the back of the neck: strap muscles, larynx, laryngopharynx, pharyngeal muscle wall and cervical vertebraehttps://www.therespiratorysystem.com/assets/img/ai/larynx-vs-pharynx/larynx-organ.webpIllustration of the larynx seen on its own, with the thyroid cartilage, hyoid bone, epiglottis and first tracheal ringshttps://www.therespiratorysystem.com/assets/img/ai/larynx-vs-pharynx/swallowing-water.webpIllustration of a person in profile drinking from a glass of water https://www.therespiratorysystem.com/left-lung/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/left-lung/hero-illustration.webpIllustration of the left lung showing its two lobes, the oblique fissure, the cardiac notch and the lingulahttps://www.therespiratorysystem.com/assets/img/diagrams/left-lung/hero.webpDiagram of the left lung from apex to base: superior lobe, cardiac notch, lingula, oblique fissure and inferior lobehttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Lungs.jpgLabeled front view of both lungs showing the left lung's cardiac notch, oblique fissure, left primary bronchus and pleurahttps://www.therespiratorysystem.com/assets/img/diagrams/left-lung/lingula-vs-middle-lobe.webpComparison chart of the lingula of the left lung and the middle lobe of the right lung: lobe, fissures, segments, airway and positionhttps://www.therespiratorysystem.com/assets/img/ai/left-lung/left-lung-beside-heart.webpIllustration of the chest from the front showing the left lung curving around the heart beside the larger right lunghttps://www.therespiratorysystem.com/assets/img/ai/left-lung/ct-scanner-room.webpIllustration of an empty hospital room with a white donut-shaped CT scanner and a padded table https://www.therespiratorysystem.com/category/lower-respiratory-tract/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/category--lower-respiratory-tract/hero-illustration.webpIllustration of the windpipe dividing into two bronchi that enter both pink lungs, seen from the fronthttps://www.therespiratorysystem.com/wp-content/uploads/2015/12/Lower-Respiratory-Tract.jpgLabeled diagram of the lower respiratory tract: trachea, bronchi, bronchioles, alveoli and the lobes of both lungshttps://www.therespiratorysystem.com/wp-content/themes/Respiratory/images/respiratory-system-diagram.jpgLabeled respiratory system diagram marking the lower respiratory tract: trachea, primary bronchi, bronchioles, alveoli, lung lobes and diaphragmhttps://www.therespiratorysystem.com/assets/img/ai/category--lower-respiratory-tract/chest-cutaway.webpIllustration of a chest in front view with translucent ribs showing both lungs, the heart between them and the diaphragm belowhttps://www.therespiratorysystem.com/assets/img/ai/category--lower-respiratory-tract/alveoli-cluster.webpIllustration of a cluster of alveoli like a bunch of grapes at the end of an airway, wrapped in tiny blood vessels https://www.therespiratorysystem.com/glossary/lung-fissures/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--lung-fissures/hero-illustration.webpIllustration of both lungs in front view with thin clefts dividing the right lung into three lobes and the left lung into twohttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--lung-fissures/hero.webpComparison chart of the oblique and horizontal fissures of the lungs: other names, which lung, lobes separated and chest wall landmarkshttps://www.therespiratorysystem.com/wp-content/uploads/2017/11/Lung-Lobes.jpgLabeled diagram of the right and left lungs showing the horizontal fissure, both oblique fissures, the lobes and the cardiac notchhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--lung-fissures/tracing-the-fissures.webpFour-step diagram showing how the oblique and horizontal lung fissures are traced on the back, side and front of the chest wallhttps://www.therespiratorysystem.com/assets/img/ai/glossary--lung-fissures/right-lung-lateral.webpIllustration of a right lung from the side with a long diagonal cleft and a shorter horizontal cleft dividing three lobeshttps://www.therespiratorysystem.com/assets/img/ai/glossary--lung-fissures/ct-scanner-room.webpIllustration of a modern CT scanner with an empty table in a bright imaging room https://www.therespiratorysystem.com/lung-volumes-and-capacities/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/lung-volumes-and-capacities/hero-illustration.webpIllustration of a seated adult breathing into a spirometer mouthpiece while a technician looks on in a clinichttps://www.therespiratorysystem.com/assets/img/diagrams/lung-volumes-and-capacities/hero.webpBar chart comparing the relative sizes of the four lung volumes and the four lung capacities in a typical adulthttps://www.therespiratorysystem.com/assets/img/diagrams/lung-volumes-and-capacities/lung-volume-layers.webpDiagram of total lung capacity divided into four stacked volumes: inspiratory reserve, tidal, expiratory reserve and residual volumehttps://www.therespiratorysystem.com/assets/img/diagrams/lung-volumes-and-capacities/minute-vs-alveolar-ventilation.webpComparison chart of minute ventilation and alveolar ventilation: definition, formula, typical resting value and dead spacehttps://www.therespiratorysystem.com/assets/img/ai/lung-volumes-and-capacities/freediver-deep-breath.webpIllustration of a freediver at the sea surface taking a big breath with the chest fully expanded https://www.therespiratorysystem.com/lungs/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/lungs/hero-illustration.webpIllustration of the two lungs in front view with the trachea, a three-lobed right lung and a two-lobed left lunghttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Lungs.jpgLabeled diagram of the human lungs showing the trachea, primary bronchi, lobes, fissures, cardiac notch, pleura and diaphragmhttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Picture-of-Lung-Segments-Anatomy.jpgSegmental anatomy of the lungs in anterior, posterior and medial views, with each bronchopulmonary segment color coded and labeledhttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Gas-Exchange-in-the-Lungs-Image.jpgDiagram of gas exchange in an alveolus: oxygen moves from the air into capillary blood while carbon dioxide moves into the alveolushttps://www.therespiratorysystem.com/assets/img/ai/lungs/lung-hilum.webpIllustration of the inner face of a left lung with the bronchus, pulmonary artery and pulmonary veins entering at the hilumhttps://www.therespiratorysystem.com/assets/img/ai/lungs/bottle-lung-model.webpIllustration of a bottle lung model on a classroom table with a balloon inflating as a rubber sheet is pulled down https://www.therespiratorysystem.com/maxillary-sinus/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/maxillary-sinus/hero-illustration.webpIllustration of a skull from the front with the two large maxillary sinuses glowing as blue air spaces inside the cheekboneshttps://www.therespiratorysystem.com/assets/img/diagrams/maxillary-sinus/hero.webpSix-step diagram of maxillary sinus drainage: mucus swept upward by cilia through the ostium and infundibulum into the middle meatushttps://www.therespiratorysystem.com/assets/img/diagrams/maxillary-sinus/sinus-and-teeth.webpLayer diagram from the maxillary sinus down to the mouth: sinus lining, bony floor, roots of the upper back teeth, alveolar bone and gumshttps://www.therespiratorysystem.com/assets/img/diagrams/maxillary-sinus/maxillary-vs-sphenoid.webpComparison chart of the maxillary sinus and the sphenoid sinus: location, bone, size, drainage, neighbors and developmenthttps://www.therespiratorysystem.com/assets/img/ai/maxillary-sinus/cheek-pressure.webpIllustration of a person calmly pressing their fingertips to the cheeks below the eyes https://www.therespiratorysystem.com/mechanics-of-breathing/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/mechanics-of-breathing/hero-illustration.webpIllustration of the chest cut open showing the dome-shaped diaphragm below the lungs inside the rib cagehttps://www.therespiratorysystem.com/assets/img/diagrams/mechanics-of-breathing/hero.webpSix-step diagram of the mechanics of breathing: muscles enlarge the chest, alveolar pressure falls, air flows in, then recoil pushes air outhttps://www.therespiratorysystem.com/assets/img/diagrams/mechanics-of-breathing/pleural-coupling.webpLayered diagram from chest wall to parietal pleura, pleural fluid, visceral pleura and lung tissue, showing how the lung follows the chesthttps://www.therespiratorysystem.com/assets/img/diagrams/mechanics-of-breathing/quiet-vs-forced.webpComparison chart of quiet breathing and forced breathing: muscles used, expiration, diaphragm movement, pressures and volumeshttps://www.therespiratorysystem.com/assets/img/ai/mechanics-of-breathing/bellows-boyle.webpIllustration of a hand bellows on a table pushing a stream of air toward a candle flame https://www.therespiratorysystem.com/mediastinum/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/mediastinum/hero-illustration.webpIllustration of the chest with see-through lungs showing the heart, great vessels, trachea and esophagus in the central compartmenthttps://www.therespiratorysystem.com/assets/img/diagrams/mediastinum/hero.webpDiagram of the divisions of the mediastinum: superior mediastinum above the sternal angle and inferior mediastinum below it, with borders and contentshttps://www.therespiratorysystem.com/assets/img/diagrams/mediastinum/inferior-front-to-back.webpLayered diagram of the inferior mediastinum from front to back: anterior, middle and posterior mediastinum with their main contentshttps://www.therespiratorysystem.com/assets/img/diagrams/mediastinum/mediastinum-vs-pericardial-cavity.webpComparison chart of the mediastinum and the pericardial cavity showing that the pericardial cavity lies inside the middle mediastinumhttps://www.therespiratorysystem.com/assets/img/ai/mediastinum/chest-cross-section.webpIllustration of a horizontal slice through the chest with the heart in the center and a lung on each side https://www.therespiratorysystem.com/muscles-of-respiration/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/muscles-of-respiration/hero-illustration.webpIllustration of the torso in front view showing the dome-shaped diaphragm below the lungs and the intercostal muscles between the ribshttps://www.therespiratorysystem.com/assets/img/diagrams/muscles-of-respiration/hero.webpCycle diagram of the muscles of respiration: diaphragm and external intercostals contract, air flows in, muscles relax, air flows outhttps://www.therespiratorysystem.com/wp-content/uploads/2018/05/Intercostal-Muscles-Function.jpgLabeled diagram of the rib cage during inhalation and exhalation, showing the intercostal muscles, ribs and diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/muscles-of-respiration/inspiration-vs-expiration.webpComparison chart of the muscles used for breathing in and breathing out during quiet and forced breathinghttps://www.therespiratorysystem.com/assets/img/ai/muscles-of-respiration/sprinter-hands-on-knees.webpIllustration of an athlete bent forward with hands on knees after a sprint, shoulders lifted as they breathe hardhttps://www.therespiratorysystem.com/assets/img/ai/muscles-of-respiration/balloon-blowing.webpIllustration of a young person blowing up a red balloon with puffed cheeks https://www.therespiratorysystem.com/nasal-cavity/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/nasal-cavity/hero-illustration.webpIllustration of the inside of the nose from the side showing the three curled turbinates on the wall of the nasal cavityhttps://www.therespiratorysystem.com/wp-content/uploads/2017/07/Nasal-Cavity.jpgLabeled side-view diagram of the nasal cavity with the conchae, meatuses, olfactory region, hard palate and nasopharynxhttps://www.therespiratorysystem.com/wp-content/uploads/2017/07/Nasal-Cavity-Bones-Diagram.jpgDiagram of the bones forming the walls of the nasal cavity, including the ethmoid, sphenoid, maxilla, palatine and nasal boneshttps://www.therespiratorysystem.com/assets/img/ai/nasal-cavity/nasal-lining-cilia.webpIllustration of the lining of the nose with hair-like cilia and mucus trapping dust and pollenhttps://www.therespiratorysystem.com/assets/img/ai/nasal-cavity/winter-breath-vapour.webpIllustration of a person in a scarf breathing out a cloud of warm vapor through the nose on a cold winter morning https://www.therespiratorysystem.com/nasal-septum/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/nasal-septum/hero-illustration.webpIllustration of a frontal cut-through of the nose with a thin midline wall dividing it into two equal air channelshttps://www.therespiratorysystem.com/assets/img/diagrams/nasal-septum/hero.webpFive-step diagram of the nasal septum from front to back: membranous septum, septal cartilage, perpendicular plate of the ethmoid and vomerhttps://www.therespiratorysystem.com/wp-content/uploads/2017/12/Bones-and-Cartilages-in-the-Nose.jpgSide view of the nose showing the septal cartilage, perpendicular plate of the ethmoid, vomer and vomeronasal cartilage of the nasal septumhttps://www.therespiratorysystem.com/assets/img/diagrams/nasal-septum/septum-vs-vomer.webpComparison chart of the nasal septum and the vomer: what each is, what it is made of, its position and flexibilityhttps://www.therespiratorysystem.com/assets/img/diagrams/nasal-septum/septum-layers.webpLayer diagram of the nasal septum: respiratory epithelium, lamina propria, perichondrium and the cartilage or bone corehttps://www.therespiratorysystem.com/assets/img/ai/nasal-septum/mucosa-vessels.webpIllustration of the pink lining of the nose with a fine network of tiny red blood vessels close to the surfacehttps://www.therespiratorysystem.com/assets/img/ai/nasal-septum/blowing-nose.webpIllustration of a person in profile gently blowing their nose into a tissue https://www.therespiratorysystem.com/nose/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/nose/hero-illustration.webpIllustration of a close-up face in three-quarter view showing the bridge, tip and nostrils of the nosehttps://www.therespiratorysystem.com/wp-content/uploads/2017/12/External-Nose.jpgLabeled diagram of the external nose showing the root, bridge, dorsum, apex, alae and nostrilshttps://www.therespiratorysystem.com/wp-content/uploads/2017/12/Bones-and-Cartilages-in-the-Nose.jpgDiagram of the bones and cartilages of the nose: nasal bones, maxilla, lateral cartilage, septal cartilage and alar cartilageshttps://www.therespiratorysystem.com/wp-content/uploads/2017/12/Nose-Anatomy-Diagram.jpgSide-view cross section of the nose showing the nasal cavity, superior, middle and inferior conchae, sinuses and nasopharynxhttps://www.therespiratorysystem.com/assets/img/ai/nose/skull-nasal-bones-profile.webpIllustration of a skull in profile showing the ivory nasal bones and the blue-grey cartilages of the nosehttps://www.therespiratorysystem.com/assets/img/ai/nose/fresh-bread-aroma.webpIllustration of a smiling person in a kitchen leaning in to smell a freshly baked loaf of bread https://www.therespiratorysystem.com/diaphragm-openings/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/diaphragm-openings/hero-illustration.webpIllustration of the diaphragm seen from below with the esophagus, aorta and vena cava passing through ithttps://www.therespiratorysystem.com/assets/img/diagrams/diaphragm-openings/hero.webpDiagram of the three main openings of the diaphragm: caval opening at T8, esophageal hiatus at T10 and aortic hiatus at T12, with their contentshttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Diaphragm.jpgLabeled view of the diaphragm from below showing the inferior vena cava, esophageal hiatus, aorta, thoracic duct, crura and phrenic nerveshttps://www.therespiratorysystem.com/assets/img/diagrams/diaphragm-openings/esophageal-vs-aortic-hiatus.webpComparison chart of the esophageal hiatus and the aortic hiatus: level, what forms them, contents and behavior when the diaphragm contractshttps://www.therespiratorysystem.com/assets/img/ai/diaphragm-openings/esophageal-hiatus-sling.webpIllustration of the esophagus passing through the diaphragm with muscle fibers looping around it like a slinghttps://www.therespiratorysystem.com/assets/img/ai/diaphragm-openings/belly-breathing-practice.webpIllustration of a person lying on a yoga mat with a hand on the belly, practicing slow diaphragmatic breathing https://www.therespiratorysystem.com/respiratory-system-organs/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-organs/hero-illustration.webpIllustration of the whole respiratory tract from the nose to the lungs inside a faint outline of the upper bodyhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-organs/hero.webpDiagram listing the organs of the respiratory system in airflow order, from the nose to the alveoli, with the diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-organs/upper-vs-lower-organs.webpComparison chart of upper respiratory tract organs and lower respiratory tract organs, their location and main jobshttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-organs/chest-wall-to-lung.webpLayer diagram from the rib cage through the parietal pleura, pleural cavity and visceral pleura to the lung tissuehttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-organs/upper-tract-side-cut.webpIllustration of the head and neck cut in side view showing the nose, throat, voice box and windpipe as one open channel https://www.therespiratorysystem.com/oropharynx/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/oropharynx/hero-illustration.webpIllustration of the back of the open mouth with the soft palate, uvula, tonsils and the back wall of the throathttps://www.therespiratorysystem.com/assets/img/diagrams/oropharynx/hero.webpDiagram of the nasal cavity, nasopharynx, oropharynx and laryngopharynx in order, showing where air and food passhttps://www.therespiratorysystem.com/wp-content/uploads/2016/09/Pharynx.jpgSide view of the head showing the nasopharynx, oropharynx and laryngopharynx behind the nasal cavity, mouth and larynxhttps://www.therespiratorysystem.com/assets/img/diagrams/oropharynx/oral-cavity-vs-oropharynx.webpComparison chart of the oral cavity and the oropharynx: location, tract, part of the tongue, lymphoid tissue, nerve and main jobshttps://www.therespiratorysystem.com/assets/img/diagrams/oropharynx/oropharynx-wall-layers.webpLayer diagram of the oropharyngeal wall from the mucosa through the submucosa, pharyngobasilar fascia and muscles to the buccopharyngeal fasciahttps://www.therespiratorysystem.com/assets/img/ai/oropharynx/palatine-tonsil.webpIllustration of a healthy palatine tonsil nestled between two curved arches on the side wall of the throathttps://www.therespiratorysystem.com/assets/img/ai/oropharynx/eating-sandwich.webpIllustration of a child at a kitchen table taking a bite of a sandwich https://www.therespiratorysystem.com/oxygen-transport/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/oxygen-transport/hero-illustration.webpIllustration of bright red blood cells flowing through a translucent artery carrying oxygenhttps://www.therespiratorysystem.com/assets/img/diagrams/oxygen-transport/hero.webpOxygen transport cycle diagram: hemoglobin loads oxygen in the lungs, carries it in the arteries, unloads it in the tissues and returns in the veinshttps://www.therespiratorysystem.com/assets/img/diagrams/oxygen-transport/hemoglobin-structure.webpLayered diagram from a red blood cell to a hemoglobin molecule, globin chain, heme group and the iron atom that binds oxygenhttps://www.therespiratorysystem.com/assets/img/diagrams/oxygen-transport/oxyhemoglobin-vs-deoxyhemoglobin.webpComparison chart of oxyhemoglobin and deoxyhemoglobin: oxygen bound, color, where each is found, shape and affinityhttps://www.therespiratorysystem.com/assets/img/ai/oxygen-transport/hemoglobin-molecule.webpIllustration of a hemoglobin molecule with four protein subunits each holding an oxygen molecule https://www.therespiratorysystem.com/oxygen-hemoglobin-dissociation-curve/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/oxygen-hemoglobin-dissociation-curve/hero-illustration.webpIllustration of red blood cells in a vessel with one cut open to show a hemoglobin molecule holding four bright red oxygen sphereshttps://www.therespiratorysystem.com/assets/img/diagrams/oxygen-hemoglobin-dissociation-curve/hero.webpBar diagram of hemoglobin oxygen saturation leaving the lungs, in resting venous blood, at half saturation, in working muscle and at very low oxygenhttps://www.therespiratorysystem.com/assets/img/diagrams/oxygen-hemoglobin-dissociation-curve/cooperative-binding.webpSix-step diagram of cooperative oxygen binding to hemoglobin, explaining the flat start, steep middle and plateau of the S-shaped curvehttps://www.therespiratorysystem.com/assets/img/diagrams/oxygen-hemoglobin-dissociation-curve/right-vs-left-shift.webpComparison chart of a right shift and a left shift of the oxygen-hemoglobin dissociation curve, with causes and effectshttps://www.therespiratorysystem.com/assets/img/ai/oxygen-hemoglobin-dissociation-curve/pregnant-walk.webpIllustration of a woman in late pregnancy walking along a tree-lined park path https://www.therespiratorysystem.com/paranasal-sinuses/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/paranasal-sinuses/hero-illustration.webpIllustration of a skull in three-quarter view with the paranasal sinuses glowing as colored air-filled spaceshttps://www.therespiratorysystem.com/wp-content/uploads/2018/03/Paranasal-Sinuses.jpgFront and side views of a face labeling the frontal, ethmoid, maxillary and sphenoid sinuses, the nasal cavity and the mucus membranehttps://www.therespiratorysystem.com/wp-content/uploads/2018/03/Paranasal-Sinuses-in-X-Ray-Image.jpgFront-facing skull X-ray with the dark air-filled frontal, ethmoid, maxillary and sphenoid sinuses labeled on both sideshttps://www.therespiratorysystem.com/wp-content/uploads/2018/03/Drainage-of-the-Sinus-Cavities-Diagram.jpgSide view of the lateral nasal wall showing where the frontal, ethmoid, maxillary and sphenoid sinuses open into the nasal cavityhttps://www.therespiratorysystem.com/assets/img/ai/paranasal-sinuses/sinuses-front-slice.webpIllustration of a front-facing slice of the face showing the large cheek sinuses and small cells between the eyes as hollow spaceshttps://www.therespiratorysystem.com/assets/img/ai/paranasal-sinuses/humming-resonance.webpIllustration of a person humming softly with a fingertip resting on the cheekbone https://www.therespiratorysystem.com/pathway-of-air/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/pathway-of-air/hero-illustration.webpIllustration of a translucent head and chest with a glowing ribbon of air travelling from the nose through the windpipe into both lungshttps://www.therespiratorysystem.com/assets/img/diagrams/pathway-of-air/hero.webpEight-step diagram of the pathway of air: nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles and alveolihttps://www.therespiratorysystem.com/wp-content/uploads/2017/10/Trace-the-Airflow-Pathway-Through-the-Respiratory-System.jpgLabeled diagram tracing the pathway of air from the nostrils and mouth through the pharynx, larynx, trachea and bronchi to the alveolihttps://www.therespiratorysystem.com/assets/img/diagrams/pathway-of-air/branching-airways.webpBranching diagram of the airways from the trachea through the main, lobar and segmental bronchi to the bronchioles and alveolihttps://www.therespiratorysystem.com/assets/img/diagrams/pathway-of-air/breathing-in-vs-out.webpComparison chart of inhaled and exhaled air: direction along the pathway, muscles, lung pressure, oxygen, carbon dioxide and moisturehttps://www.therespiratorysystem.com/assets/img/ai/pathway-of-air/windpipe-rings.webpIllustration of the windpipe with stacked C-shaped cartilage rings dividing at the bottom into two bronchihttps://www.therespiratorysystem.com/assets/img/ai/pathway-of-air/dandelion-blow.webpIllustration of a child blowing on a dandelion seed head in a sunny meadow as the seeds float away https://www.therespiratorysystem.com/pharynx/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/pharynx/hero-illustration.webpIllustration of the throat from the side with the upper, middle and lower parts of the pharynx shown in different tintshttps://www.therespiratorysystem.com/wp-content/uploads/2016/09/Pharynx.jpgSide view of the head and neck labeling the nasopharynx, oropharynx and laryngopharynx, with the soft palate, epiglottis, larynx and esophagushttps://www.therespiratorysystem.com/assets/img/ai/pharynx/choir-singing.webpIllustration of a choir of singers standing in rows with open mouths in a bright hallhttps://www.therespiratorysystem.com/assets/img/ai/pharynx/pharyngeal-constrictors.webpIllustration of the back of the throat showing three overlapping bands of constrictor muscle around the pharynx https://www.therespiratorysystem.com/phrenic-nerve/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/phrenic-nerve/hero-illustration.webpIllustration of a see-through torso showing a golden phrenic nerve running from the neck down to the diaphragm on each sidehttps://www.therespiratorysystem.com/assets/img/diagrams/phrenic-nerve/hero.webpSix-step diagram of the phrenic nerve course from the C3 to C5 roots in the neck, through the chest beside the heart, to the diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/phrenic-nerve/right-vs-left.webpComparison chart of the right and left phrenic nerves: length, path in the upper chest, relation to the heart and where each enters the diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/phrenic-nerve/breathing-control-loop.webpCycle diagram of breathing control: brainstem, phrenic motor neurons, phrenic nerve, diaphragm contraction, airflow and feedbackhttps://www.therespiratorysystem.com/assets/img/ai/phrenic-nerve/diaphragm-nerve-branches.webpIllustration of the diaphragm dome with golden nerve branches spreading across its muscle surface like leaf veins https://www.therespiratorysystem.com/pleura/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/pleura/hero-illustration.webpIllustration of a chest cutaway showing a lung covered by a glossy membrane and the matching lining on the inside of the chest wallhttps://www.therespiratorysystem.com/assets/img/diagrams/pleura/hero.webpLayered diagram of the pleura from the chest wall inward: endothoracic fascia, parietal pleura, pleural cavity, visceral pleura and lunghttps://www.therespiratorysystem.com/assets/img/diagrams/pleura/visceral-vs-parietal-pleura.webpComparison chart of the visceral pleura and the parietal pleura: location, parts, origin, nerve and blood supplyhttps://www.therespiratorysystem.com/assets/img/ai/pleura/wet-glass-slides.webpIllustration of two wet glass slides stuck together by a thin film of water while one slides over the other https://www.therespiratorysystem.com/pneumocytes/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/pneumocytes/alveolus-cells.webpIllustration of an alveolus cut open, showing flat type I pneumocytes lining the wall and rounded type II pneumocytes releasing surfactanthttps://www.therespiratorysystem.com/assets/img/diagrams/pneumocytes/hero.webpComparison chart of type I and type II pneumocytes: shape, share of alveolar surface, position, main job and role in repairhttps://www.therespiratorysystem.com/assets/img/diagrams/pneumocytes/surface-vs-number.webpBar chart showing that type I pneumocytes cover nearly all of the alveolar surface while type II pneumocytes are the more numerous cellshttps://www.therespiratorysystem.com/assets/img/diagrams/pneumocytes/alveolar-repair.webpFive-step diagram of alveolar repair in which type II pneumocytes divide, spread and flatten into new type I pneumocytes https://www.therespiratorysystem.com/pulmonary-circulation/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/pulmonary-circulation/hero-illustration.webpIllustration of the heart and lungs with blue arteries entering the lungs and red veins returning to the hearthttps://www.therespiratorysystem.com/assets/img/diagrams/pulmonary-circulation/hero.webpSix-step diagram of the pulmonary circulation pathway from the right ventricle through the lungs to the left atriumhttps://www.therespiratorysystem.com/assets/img/diagrams/pulmonary-circulation/pulmonary-artery-branches.webpBranching diagram of the pulmonary arteries from the pulmonary trunk to lobar and segmental arteries, arterioles and alveolar capillarieshttps://www.therespiratorysystem.com/assets/img/diagrams/pulmonary-circulation/pulmonary-vs-systemic.webpComparison chart of pulmonary circulation and systemic circulation: chambers, blood oxygen, pressure, resistance and response to low oxygenhttps://www.therespiratorysystem.com/assets/img/ai/pulmonary-circulation/pulmonary-veins-back.webpIllustration of the heart seen from behind with four red pulmonary veins entering the left atrium https://www.therespiratorysystem.com/glossary/pulmonary-lobule/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--pulmonary-lobule/hero-illustration.webpIllustration of a small polyhedral block of lung tissue, a pulmonary lobule, cut open to show its airways and air sacshttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--pulmonary-lobule/hero.webpNested diagram of lung units from lung to lobe, segment, secondary pulmonary lobule, acinus and alveolushttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--pulmonary-lobule/airways-inside-a-lobule.webpBranching diagram of airways inside a pulmonary lobule, from the lobular bronchiole to respiratory bronchioles and alveolar sacshttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--pulmonary-lobule/lobule-vs-acinus.webpComparison chart of the pulmonary lobule and the pulmonary acinus: definition, size, entering airway, contents and zonehttps://www.therespiratorysystem.com/assets/img/ai/glossary--pulmonary-lobule/radiologist-ct-review.webpIllustration of a radiologist at a desk reviewing chest scan images on two monitors in a quiet reading room https://www.therespiratorysystem.com/pulmonary-surfactant/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/pulmonary-surfactant/hero-illustration.webpIllustration of a cluster of air sacs, one cut open to show a thin shiny golden film of surfactant on its inner surfacehttps://www.therespiratorysystem.com/assets/img/diagrams/pulmonary-surfactant/hero.webpComparison chart of alveoli with and without pulmonary surfactant: surface tension, collapse, effort to inflate and fluid in the air sacshttps://www.therespiratorysystem.com/assets/img/diagrams/pulmonary-surfactant/surfactant-life-cycle.webpCycle diagram of the surfactant life cycle: made in type II cells, stored in lamellar bodies, secreted, spread as a film, taken back up and recycledhttps://www.therespiratorysystem.com/assets/img/diagrams/pulmonary-surfactant/where-surfactant-sits.webpLayered diagram showing the surfactant film and hypophase on top of the alveolar epithelium, basement membrane and capillary wallhttps://www.therespiratorysystem.com/assets/img/ai/pulmonary-surfactant/newborn-sleeping-hospital.webpIllustration of a newborn baby in a knitted cap sleeping peacefully in a hospital bassinet https://www.therespiratorysystem.com/respiratory-chemoreceptors/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-chemoreceptors/hero-illustration.webpIllustration of the carotid artery splitting in the neck with a tiny bean-shaped carotid body at the forkhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-chemoreceptors/hero.webpFeedback loop diagram: rising carbon dioxide is detected by chemoreceptors, the medulla increases breathing, and carbon dioxide returns to normalhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-chemoreceptors/glomus-cell-steps.webpSix-step diagram of how a carotid body glomus cell detects low oxygen and signals the brainstem to increase breathinghttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-chemoreceptors/central-vs-peripheral.webpComparison chart of central and peripheral chemoreceptors: location, stimulus, response to low oxygen, speed and nerve pathwayhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-chemoreceptors/holding-breath-pool.webpIllustration of a swimmer calmly holding their breath underwater in a clear pool with bubbles rising https://www.therespiratorysystem.com/respiratory-diseases/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-diseases/hero-illustration.webpIllustration of a stethoscope, an anatomical lung model and an inhaler on a clinic deskhttps://www.therespiratorysystem.com/wp-content/themes/Respiratory/images/respiratory-system-diagram.jpgLabeled diagram of the respiratory system marking the upper tract (nose, sinuses, pharynx, larynx) and lower tract (trachea, bronchi, lungs)https://www.therespiratorysystem.com/assets/img/ai/respiratory-diseases/city-smog.webpIllustration of a city skyline at dusk under a layer of smog above a busy roadhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-diseases/forest-walk.webpIllustration of friends walking along a sunny forest trail in clean fresh air https://www.therespiratorysystem.com/respiratory-epithelium/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-epithelium/hero-illustration.webpIllustration of a slice of airway lining with tall ciliated cells, mucus-releasing goblet cells and small cells at the basehttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-epithelium/hero.webpLayer diagram of the respiratory mucosa: mucus, periciliary fluid, pseudostratified ciliated epithelium, basement membrane, lamina propriahttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-epithelium/ciliated-vs-goblet.webpComparison chart of ciliated columnar cells and goblet cells in the respiratory epithelium: shape, surface, product and jobhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-epithelium/lining-along-the-airways.webpBranching diagram showing how the airway lining changes from pseudostratified in the trachea to simple squamous in the alveolihttps://www.therespiratorysystem.com/assets/img/ai/respiratory-epithelium/trachea-cross-ring.webpIllustration of a slice of the windpipe showing a C-shaped cartilage ring and a thin, moist, glistening lining https://www.therespiratorysystem.com/respiratory-membrane/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-membrane/hero-illustration.webpIllustration of a red blood cell passing through a capillary pressed against an almost transparent alveolar wallhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-membrane/hero.webpLayered diagram of the respiratory membrane from alveolar air to capillary blood, showing its six layers from surfactant film to endotheliumhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-membrane/thin-vs-thick-side.webpComparison chart of the thin side and the thick side of the blood-air barrier around a lung capillaryhttps://www.therespiratorysystem.com/wp-content/uploads/2017/06/Labeled-Diagram-of-Alveoli-Gas-Exchange.jpgLabeled diagram of an alveolus beside a capillary, with the alveolar epithelium, capillary wall, surfactant and gas diffusionhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-membrane/soap-bubble.webpIllustration of a large shimmering soap bubble in front of a blurred green gardenhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-membrane/capillary-basket.webpIllustration of a fine mesh of red and blue capillaries wrapped into a basket shape around an empty rounded space https://www.therespiratorysystem.com/respiratory-physiology/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-physiology/hero-illustration.webpIllustration of two inflated lungs above the diaphragm with a glowing network of blood vessels, seen at a three-quarter anglehttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-physiology/hero.webpFive-step diagram of respiratory physiology: ventilation, external respiration, gas transport, internal respiration and cellular respirationhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-physiology/lung-volumes-bars.webpBar chart comparing the relative sizes of tidal volume, expiratory reserve volume, residual volume and inspiratory reserve volumehttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-physiology/breathing-control-loop.webpCycle diagram of breathing control: rising carbon dioxide is sensed, the brainstem drives deeper breathing and carbon dioxide fallshttps://www.therespiratorysystem.com/assets/img/ai/respiratory-physiology/breathing-test.webpIllustration of a person with a nose clip breathing into a handheld spirometer mouthpiece while a technician watches https://www.therespiratorysystem.com/respiratory-system-diagram/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-diagram/hero-illustration.webpIllustration of the whole respiratory system from the nose and throat to the lungs inside a translucent torso silhouettehttps://www.therespiratorysystem.com/wp-content/themes/Respiratory/images/respiratory-system-diagram.jpgLabeled respiratory system diagram showing the nasal cavity, pharynx, larynx, trachea, bronchi, both lungs with their lobes, alveoli and the diaphragmhttps://www.therespiratorysystem.com/wp-content/uploads/2015/12/Upper-Respiratory-Tract.jpgSide-view upper respiratory tract diagram labeling the nasal cavity, sinuses, palate, oral cavity, pharynx, larynx and vocal cordshttps://www.therespiratorysystem.com/wp-content/uploads/2015/12/Lower-Respiratory-Tract.jpgLower respiratory tract diagram labeling the larynx, trachea, primary bronchi, both lungs, bronchioles, alveolar sac, alveoli, ribs and diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-diagram/airway-branches.webpBranching chart of the airways in a respiratory system diagram, from the trachea through the bronchi and bronchioles to the alveolihttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-diagram/how-to-label.webpSix-step guide to labeling a respiratory system diagram in the order air flows, from the nostrils to the alveoli and diaphragmhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-diagram/student-drawing.webpIllustration of a student at a desk drawing a simple outline of two lungs and a windpipe in a notebookhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-diagram/classroom-torso-model.webpIllustration of a classroom torso model with one pink lung lifted out beside it on a teacher's desk https://www.therespiratorysystem.com/respiratory-system-facts/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-facts/hero-illustration.webpIllustration of a child blowing the seeds off a dandelion in a golden meadowhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-facts/hero.webpComparison chart of inhaled and exhaled air: oxygen, carbon dioxide, nitrogen, water vapor and temperaturehttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-facts/airway-branching.webpBranching diagram of the airways from the trachea through the bronchi and bronchioles to the alveolihttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-facts/breathing-rate-by-age.webpBar chart showing that resting breathing rate is fastest in newborns and slows through childhood to the adult ratehttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-facts/sponge-floating.webpIllustration of a natural sponge floating on the water in a clear glass bowl https://www.therespiratorysystem.com/respiratory-system-histology/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-histology/hero-illustration.webpIllustration of a laboratory microscope with a pink and purple stained tissue slide on its stagehttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-histology/hero.webpBranching diagram of respiratory system histology from the trachea to the alveoli, showing how cartilage, glands and epithelium changehttps://www.therespiratorysystem.com/wp-content/uploads/2017/03/Trachea-Cross-Section-Anatomy.jpgLabeled cross section of the trachea showing the pseudostratified epithelium, submucosa, hyaline cartilage ring, trachealis muscle and adventitiahttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-histology/airway-wall-layers.webpLayer diagram of the tracheal wall from the adventitia through hyaline cartilage, submucosa and lamina propria to the respiratory epitheliumhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-histology/ciliated-cells.webpIllustration of magnified ciliated cells with goblet cells and dust trapped in a layer of mucushttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-histology/alveolar-wall-magnified.webpIllustration of a very thin alveolar wall with a capillary where red blood cells pass in single file https://www.therespiratorysystem.com/respiratory-system-quiz/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-quiz/hero-illustration.webpIllustration of a student at a desk in a library studying beside a plastic lung model and an open notebookhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-quiz/hero.webpSix-step study map for a respiratory system quiz: label the parts, know each job, tissues, breathing, gas transport and lung volumeshttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-quiz/inhalation-vs-exhalation.webpComparison chart of breathing in and quiet breathing out: diaphragm, intercostal muscles, chest volume, lung pressure, airflow and energyhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-quiz/lung-volumes-bars.webpBar chart comparing the relative sizes of tidal volume, expiratory and inspiratory reserve, residual volume, vital capacity and total lung capacityhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-quiz/lung-microscope.webpIllustration of a microscope on a laboratory bench with a stained lung tissue slide beside it https://www.therespiratorysystem.com/respiratory-system-worksheet/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-worksheet/hero-illustration.webpIllustration of a desk with a sheet showing a pencil outline of two lungs and a windpipe, colored pencils beside ithttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-worksheet/hero.webpRespiratory system labeling worksheet with eight blank lines and a clue for each stop on the path of air, from nostrils to alveolihttps://www.therespiratorysystem.com/wp-content/uploads/2017/10/Trace-the-Airflow-Pathway-Through-the-Respiratory-System.jpgLabeled diagram of the pathway of air through the respiratory system, from the nostrils and nasal cavity to the bronchioles and alveolihttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-worksheet/breathing-cycle-key.webpCycle diagram of one breath: the diaphragm contracts, the chest enlarges and air flows in, then the diaphragm relaxes and air flows outhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-worksheet/coloring-lungs.webpIllustration of a child coloring a drawing of lungs with red and blue crayons at a tablehttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-worksheet/teacher-lung-model.webpIllustration of a teacher pointing at a large lung model in a bright classroom while students watch from their desks https://www.therespiratorysystem.com/rib-cage/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/rib-cage/hero-illustration.webpIllustration of the rib cage seen from the front with the breastbone and ribs enclosing the lungshttps://www.therespiratorysystem.com/assets/img/diagrams/rib-cage/hero.webpSix-step diagram of how the rib cage, diaphragm and intercostal muscles enlarge the chest during inhalationhttps://www.therespiratorysystem.com/assets/img/diagrams/rib-cage/pump-handle-vs-bucket-handle.webpComparison chart of the pump-handle and bucket-handle movements of the ribs during breathinghttps://www.therespiratorysystem.com/assets/img/ai/rib-cage/ribs-side-view.webpIllustration of the rib cage from the side showing true, false and floating ribs in different tints https://www.therespiratorysystem.com/right-lung/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/right-lung/hero-illustration.webpIllustration of the right lung on its own in side view with its three lobes in different shades of pinkhttps://www.therespiratorysystem.com/assets/img/diagrams/right-lung/hero.webpDiagram of the right lung from apex to base: superior lobe, horizontal fissure, middle lobe, oblique fissure and inferior lobehttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Picture-of-Lung-Segments-Anatomy.jpgSegmental anatomy of the lungs in anterior, posterior and medial views, with the right lung's ten segments color coded and labeledhttps://www.therespiratorysystem.com/assets/img/diagrams/right-lung/right-lobe-sizes.webpBar chart comparing the relative size of the right inferior, superior and middle lobes, from largest to smallesthttps://www.therespiratorysystem.com/assets/img/ai/right-lung/right-lung-medial-hilum.webpIllustration of the inner surface of the right lung showing where the bronchus, artery and veins enter at its roothttps://www.therespiratorysystem.com/assets/img/ai/right-lung/right-lung-with-liver.webpIllustration of the chest cut in front view showing the right lung, the heart tilted to the left and the liver under the right diaphragm https://www.therespiratorysystem.com/sense-of-smell/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/sense-of-smell/hero-illustration.webpIllustration of a person in a sunlit garden leaning in to smell a bouquet of pink and red roseshttps://www.therespiratorysystem.com/assets/img/diagrams/sense-of-smell/hero.webpSix-step diagram of how we smell: odorants are inhaled, dissolve in nasal mucus, bind receptors and signal the olfactory bulb and brainhttps://www.therespiratorysystem.com/assets/img/diagrams/sense-of-smell/olfactory-layers.webpLayer diagram of the olfactory region: mucus, olfactory epithelium, lamina propria, cribriform plate and olfactory bulbhttps://www.therespiratorysystem.com/assets/img/diagrams/sense-of-smell/respiratory-vs-olfactory.webpComparison chart of respiratory epithelium and olfactory epithelium: location, job, cells, cilia, mucus source and colorhttps://www.therespiratorysystem.com/assets/img/ai/sense-of-smell/olfactory-bulb-cutaway.webpIllustration of a side cutaway of the nose roof with fine nerve threads rising to the olfactory bulb under the brain https://www.therespiratorysystem.com/sphenoid-sinus/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/sphenoid-sinus/hero-illustration.webpIllustration of a skull cut in half showing an air-filled sinus deep in the center behind the nasal cavityhttps://www.therespiratorysystem.com/assets/img/diagrams/sphenoid-sinus/hero.webpStep diagram tracing the route from the nostril through the upper nasal cavity and sphenoethmoidal recess to the sphenoid sinushttps://www.therespiratorysystem.com/assets/img/diagrams/sphenoid-sinus/sphenoid-sinus-lining.webpLayer diagram of the sphenoid sinus wall from the bone through periosteum, lamina propria and ciliated epithelium to the mucus layerhttps://www.therespiratorysystem.com/assets/img/diagrams/sphenoid-sinus/sphenoid-vs-maxillary.webpComparison chart of the sphenoid sinus and the maxillary sinus by bone, position, size, drainage, neighbors and developmenthttps://www.therespiratorysystem.com/assets/img/ai/sphenoid-sinus/sphenoid-bone.webpIllustration of the isolated sphenoid bone shaped like a butterfly with outspread wings https://www.therespiratorysystem.com/glossary/terminal-and-respiratory-bronchioles/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--terminal-and-respiratory-bronchioles/hero-illustration.webpIllustration of a small lung lobule cut open showing a tiny airway branching into fine tubes that end in clusters of air sacshttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--terminal-and-respiratory-bronchioles/hero.webpBranching diagram from small bronchi through lobular, terminal and respiratory bronchioles to alveolar ducts and sacshttps://www.therespiratorysystem.com/wp-content/uploads/2017/04/Bronchioles.jpgLabeled illustration of a lobular bronchiole dividing into terminal and respiratory bronchioles, alveolar ducts and alveolar sacshttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--terminal-and-respiratory-bronchioles/terminal-bronchiole-wall.webpLayer diagram of a terminal bronchiole wall: adventitia, smooth muscle, lamina propria and cuboidal epithelium with club cellshttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--terminal-and-respiratory-bronchioles/terminal-vs-respiratory.webpComparison chart of terminal bronchioles and respiratory bronchioles: zone, alveoli, gas exchange, lining and smooth musclehttps://www.therespiratorysystem.com/assets/img/ai/glossary--terminal-and-respiratory-bronchioles/bronchiole-club-cells.webpIllustration of the dome-topped club cells and a few ciliated cells lining a terminal bronchiolehttps://www.therespiratorysystem.com/assets/img/ai/glossary--terminal-and-respiratory-bronchioles/alveolar-duct-sacs.webpIllustration of an alveolar duct cut open, with openings along its wall leading into grape-like alveolar sacs https://www.therespiratorysystem.com/2026-11-02https://www.therespiratorysystem.com/wp-content/themes/Respiratory/images/respiratory-system-diagram.jpgRespiratory system diagram https://www.therespiratorysystem.com/respiratory-system-for-kids/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-for-kids/hero-illustration.webpIllustration of a cheerful child blowing a big shiny soap bubble in a sunny parkhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-for-kids/hero.webpSix-step kids diagram of the path of air: nose or mouth, throat, voice box, windpipe, bronchi and air sacs in the lungshttps://www.therespiratorysystem.com/wp-content/uploads/2017/10/Trace-the-Airflow-Pathway-Through-the-Respiratory-System.jpgLabeled picture of the respiratory system: nasal cavity, mouth, pharynx, larynx, trachea, bronchi, lungs, alveoli and diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-for-kids/breathing-in-vs-out.webpKids comparison chart of breathing in and breathing out: what the diaphragm, ribs, chest and lungs dohttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-for-kids/air-sac-swap.webpKids diagram of an air sac next to a tiny blood vessel: oxygen moves into the blood and carbon dioxide moves outhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-for-kids/bottle-lung-model.webpIllustration of a teacher showing children a home-made lung model made from a plastic bottle and balloonhttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-for-kids/child-with-tissue.webpIllustration of a smiling child holding a tissue to the nose in a cozy living room https://www.therespiratorysystem.com/thoracic-cavity/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/thoracic-cavity/hero-illustration.webpIllustration of the empty thoracic cage with the ribs, sternum, collarbones and spine in three-quarter viewhttps://www.therespiratorysystem.com/assets/img/diagrams/thoracic-cavity/hero.webpComparison diagram of the three compartments of the thoracic cavity: the two pleural cavities and the mediastinumhttps://www.therespiratorysystem.com/assets/img/diagrams/thoracic-cavity/chest-wall-layers.webpLayered diagram of the chest wall from the skin inward: skin, muscles, ribs and intercostal muscles, endothoracic fascia, parietal pleurahttps://www.therespiratorysystem.com/assets/img/diagrams/thoracic-cavity/thoracic-vs-abdominal-cavity.webpComparison chart of the thoracic cavity and the abdominal cavity: position, walls, lining, organs and changes during breathinghttps://www.therespiratorysystem.com/assets/img/ai/thoracic-cavity/chest-cross-section.webpIllustration of a horizontal slice through the chest showing the ribs, both lungs, the heart, the aorta, the esophagus and the spine https://www.therespiratorysystem.com/tidal-volume/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/tidal-volume/hero-illustration.webpIllustration of half-inflated lungs inside a resting torso, front view, beside a glass beaker half filled with pale blue misthttps://www.therespiratorysystem.com/assets/img/diagrams/tidal-volume/hero.webpCycle diagram of one tidal breath: diaphragm contracts, about 500 mL flows in, muscles relax, air flows out, lungs return to FRChttps://www.therespiratorysystem.com/assets/img/diagrams/tidal-volume/tidal-volume-vs-lung-volumes.webpBar chart showing tidal volume as a small fraction of the reserve volumes, residual volume and vital capacity of an adulthttps://www.therespiratorysystem.com/assets/img/diagrams/tidal-volume/rest-vs-exercise.webpComparison chart of tidal volume, breathing rate, ventilation and breathing muscles at quiet rest and during hard exercisehttps://www.therespiratorysystem.com/assets/img/ai/tidal-volume/bottle-spirometer-lab.webpIllustration of a science experiment with an upside-down bottle in a water tub and a breathing tube to measure breath volume https://www.therespiratorysystem.com/trachea/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/trachea/hero-illustration.webpIllustration looking down inside the windpipe, a glossy pink tunnel with ridges, to where it splits into two brancheshttps://www.therespiratorysystem.com/wp-content/uploads/2017/03/Trachea.jpgLabeled diagram of the trachea running from the larynx to its bifurcation into the right and left bronchi inside the lungshttps://www.therespiratorysystem.com/wp-content/uploads/2017/03/Carina-of-Trachea.jpgBifurcation of the trachea viewed from above, showing the carina ridge between the openings of the right and left bronchihttps://www.therespiratorysystem.com/wp-content/uploads/2017/03/Trachea-Cross-Section-Anatomy.jpgCross section of the trachea showing the mucosa, submucosa, C-shaped hyaline cartilage ring, adventitia, trachealis muscle and esophagushttps://www.therespiratorysystem.com/assets/img/ai/trachea/thyroid-and-trachea-front.webpIllustration of the front of the neck showing the ribbed windpipe with the butterfly-shaped thyroid gland around ithttps://www.therespiratorysystem.com/assets/img/ai/trachea/birthday-candles.webpIllustration of a child in profile blowing out birthday candles on a cake in one strong breath https://www.therespiratorysystem.com/esophagus-vs-trachea/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/esophagus-vs-trachea/hero-illustration.webpIllustration of the neck in side view with the ribbed windpipe in front of the soft pink food pipehttps://www.therespiratorysystem.com/assets/img/diagrams/esophagus-vs-trachea/hero.webpComparison chart of the trachea and esophagus: what each carries, position, support, lining, muscle, ending and body systemhttps://www.therespiratorysystem.com/assets/img/diagrams/esophagus-vs-trachea/front-to-back.webpLayer diagram of the neck from front to back: skin and strap muscles, thyroid gland, trachea, esophagus and vertebral columnhttps://www.therespiratorysystem.com/assets/img/diagrams/esophagus-vs-trachea/swallowing.webpSix-step diagram of swallowing showing how the airway closes and food enters the esophagus instead of the tracheahttps://www.therespiratorysystem.com/assets/img/ai/esophagus-vs-trachea/drinking-water-kitchen.webpIllustration of a person in profile drinking a glass of water in a kitchen https://www.therespiratorysystem.com/category/upper-respiratory-tract/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/category--upper-respiratory-tract/hero-illustration.webpIllustration of a head and neck cut open from the side showing the nose, sinuses, throat and voice boxhttps://www.therespiratorysystem.com/wp-content/uploads/2015/12/Upper-Respiratory-Tract.jpgLabeled diagram of the upper respiratory tract: nasal cavity, paranasal sinuses, nostril, oral cavity, pharynx, larynx and vocal cordshttps://www.therespiratorysystem.com/wp-content/themes/Respiratory/images/respiratory-system-diagram.jpgLabeled diagram of the human respiratory system showing the nasal cavity, pharynx, larynx and trachea above the lungshttps://www.therespiratorysystem.com/assets/img/ai/category--upper-respiratory-tract/sniffing-flower.webpIllustration of a person in profile smelling a daisy in a sunny meadow with pollen drifting in the airhttps://www.therespiratorysystem.com/assets/img/ai/category--upper-respiratory-tract/child-with-cold.webpIllustration of a child with a cold resting under a blanket on a sofa with a tissue and a warm drink https://www.therespiratorysystem.com/upper-vs-lower-respiratory-tract/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/upper-vs-lower-respiratory-tract/hero-illustration.webpIllustration of a side cutaway of a head and chest showing the airway from nose and throat down to the lungshttps://www.therespiratorysystem.com/assets/img/diagrams/upper-vs-lower-respiratory-tract/hero.webpComparison chart of the upper and lower respiratory tract: parts, location, main job, gas exchange, support, extra roles and infectionshttps://www.therespiratorysystem.com/assets/img/diagrams/upper-vs-lower-respiratory-tract/airway-path-upper-to-lower.webpEight-step diagram of a breath moving through the upper respiratory tract from the nose to the larynx and the lower tract from trachea to alveolihttps://www.therespiratorysystem.com/wp-content/uploads/2017/10/Trace-the-Airflow-Pathway-Through-the-Respiratory-System.jpgLabeled diagram of the airway from the nostrils, nasal cavity, pharynx and larynx down the trachea and bronchi to the alveolihttps://www.therespiratorysystem.com/assets/img/ai/upper-vs-lower-respiratory-tract/trachea-rings.webpIllustration of the windpipe as a ribbed tube of stacked C-shaped cartilage rings that divides into two bronchihttps://www.therespiratorysystem.com/assets/img/ai/upper-vs-lower-respiratory-tract/resting-with-a-cold.webpIllustration of a person resting on a sofa under a blanket with a mug of tea and a box of tissues nearby https://www.therespiratorysystem.com/glossary/uvula/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--uvula/hero-illustration.webpIllustration of the back of an open mouth showing the soft palate arch and the teardrop-shaped uvula hanging in the middlehttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--uvula/hero.webpFive-step diagram showing how the soft palate and uvula rise to close off the nasopharynx during a swallowhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--uvula/uvula-tissues.webpLayer diagram of the uvula: mucous membrane, then glands and connective tissue, then the musculus uvulae at the corehttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--uvula/uvula-vs-epiglottis.webpComparison chart of the uvula and the epiglottis: location, tissue, shape, what each guards and their roleshttps://www.therespiratorysystem.com/assets/img/ai/glossary--uvula/yawning-person.webpIllustration of a person yawning widely on a sofa in a bright living room https://www.therespiratorysystem.com/vital-capacity/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/vital-capacity/hero-illustration.webpIllustration of a young woman blowing up a large colorful balloon outdoors on a sunny dayhttps://www.therespiratorysystem.com/assets/img/diagrams/vital-capacity/hero.webpBar chart showing vital capacity as the sum of inspiratory reserve volume, tidal volume and expiratory reserve volume, without residual volumehttps://www.therespiratorysystem.com/assets/img/diagrams/vital-capacity/how-vital-capacity-is-measured.webpSix-step diagram of a vital capacity test: sit with nose clip, breathe normally, inhale fully, exhale completely, read volume, comparehttps://www.therespiratorysystem.com/assets/img/diagrams/vital-capacity/restrictive-vs-obstructive.webpComparison chart of how restrictive and obstructive lung conditions change vital capacity, total lung capacity, residual volume and FEV1/FVChttps://www.therespiratorysystem.com/assets/img/ai/vital-capacity/swimmer-start-block.webpIllustration of a swimmer at the pool edge drawing in a deep breath before diving in https://www.therespiratorysystem.com/vocal-cords/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/vocal-cords/hero-illustration.webpIllustration looking down into the larynx at two pearly-white vocal folds forming a V around the airway openinghttps://www.therespiratorysystem.com/assets/img/diagrams/vocal-cords/hero.webpComparison chart of the true vocal cords and the false vocal cords: position, color, core, lining, vibration and main jobshttps://www.therespiratorysystem.com/wp-content/uploads/2016/11/Larynx-Diagram.jpgSide view of the head and neck showing the vocal cord inside the larynx between the supraglottis and subglottis, above the tracheahttps://www.therespiratorysystem.com/assets/img/diagrams/vocal-cords/vocal-fold-layers.webpLayer diagram of a vocal fold from the epithelium through the three layers of lamina propria to the vocalis musclehttps://www.therespiratorysystem.com/assets/img/diagrams/vocal-cords/vocal-cord-positions.webpSix-step diagram of vocal cord positions during quiet breathing, deep breathing, speaking, whispering, swallowing and coughinghttps://www.therespiratorysystem.com/assets/img/ai/vocal-cords/stage-singer.webpIllustration of a singer in a warm spotlight holding a microphone and singing on a stagehttps://www.therespiratorysystem.com/assets/img/ai/vocal-cords/grandfather-reading-aloud.webpIllustration of an elderly man reading a picture book aloud to a small child in a cozy living room https://www.therespiratorysystem.com/which-lung-is-bigger/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/which-lung-is-bigger/hero-illustration.webpIllustration of the two lungs in front view, with the wider three-lobed right lung beside the narrower two-lobed left lunghttps://www.therespiratorysystem.com/assets/img/diagrams/which-lung-is-bigger/hero.webpSide-by-side chart comparing the right and left lung: size, width, length, lobes, fissures, segments and heart impressionhttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Lungs.jpgLabeled front view of both lungs: the three-lobed right lung and the narrower two-lobed left lung with its cardiac notchhttps://www.therespiratorysystem.com/assets/img/diagrams/which-lung-is-bigger/why-the-right-lung-is-bigger.webpSix-step diagram explaining why the right lung is bigger: lung bud branching, heart position, cardiac notch, liver and the result for each lunghttps://www.therespiratorysystem.com/assets/img/ai/which-lung-is-bigger/heart-in-the-notch.webpIllustration of the heart nestled in a curved notch of the left lung while the right lung keeps a full rounded shapehttps://www.therespiratorysystem.com/assets/img/ai/which-lung-is-bigger/people-different-sizes.webpIllustration of a tall adult and a small child holding hands on a park path, seen from behind https://www.therespiratorysystem.com/why-do-we-sneeze/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/why-do-we-sneeze/hero-illustration.webpIllustration of a young woman in a spring garden sneezing into the crook of her elbow among flowers and drifting pollenhttps://www.therespiratorysystem.com/assets/img/diagrams/why-do-we-sneeze/hero.webpSix-step diagram of the sneeze reflex from an irritant in the nose through the trigeminal nerve and brainstem to the blast of airhttps://www.therespiratorysystem.com/assets/img/diagrams/why-do-we-sneeze/sneeze-vs-cough.webpComparison chart of a sneeze and a cough: area cleared, trigger, sensory nerve, air route, voluntary control and eyeshttps://www.therespiratorysystem.com/assets/img/ai/why-do-we-sneeze/grinding-pepper.webpIllustration of a hand grinding black pepper over a plate with tiny specks floating in the air https://www.therespiratorysystem.com/adenoids/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/adenoids/hero-illustration.webpIllustration of a child's head cut in side view showing the pink adenoid tissue on the roof of the throat behind the nosehttps://www.therespiratorysystem.com/assets/img/diagrams/adenoids/hero.webpComparison chart of the adenoids and the palatine tonsils by name, number, location, visibility, lining, surface and what each sampleshttps://www.therespiratorysystem.com/assets/img/diagrams/adenoids/air-past-the-adenoids.webpStep diagram of inhaled air passing from the nostrils through the nasal cavity and choanae over the adenoids into the oropharynxhttps://www.therespiratorysystem.com/assets/img/diagrams/adenoids/adenoid-size-with-age.webpBar chart showing the relative size of the adenoids, small at birth, largest in early childhood and shrinking through adolescence into adulthoodhttps://www.therespiratorysystem.com/assets/img/ai/adenoids/pediatric-checkup.webpIllustration of a smiling child holding a teddy bear while a doctor gently examines the neck https://www.therespiratorysystem.com/breathing-patterns/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/breathing-patterns/hero-illustration.webpIllustration of a calm adult lying on a yoga mat with one hand on the belly and one on the chest, breathing slowly and evenlyhttps://www.therespiratorysystem.com/assets/img/diagrams/breathing-patterns/hero.webpComparison chart of a normal breathing pattern (eupnea) and abnormal breathing patterns by rate, depth, rhythm and efforthttps://www.therespiratorysystem.com/assets/img/diagrams/breathing-patterns/resting-rates.webpBar chart comparing resting breathing rates in adult bradypnea, normal adults, adult tachypnea and newbornshttps://www.therespiratorysystem.com/assets/img/diagrams/breathing-patterns/cheyne-stokes-cycle.webpCycle diagram of Cheyne-Stokes breathing: breaths deepen, peak, fade, pause in apnea and restart as carbon dioxide buildshttps://www.therespiratorysystem.com/assets/img/ai/breathing-patterns/jogger-deep-breath.webpIllustration of a jogger pausing in a park at sunrise with hands on hips, taking a deep recovery breath https://www.therespiratorysystem.com/breathing-at-high-altitude/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/breathing-at-high-altitude/climber-high-altitude.webpIllustration of a mountain climber pausing on a snowy ridge at high altitude and breathing hard in the thin, cold airhttps://www.therespiratorysystem.com/assets/img/diagrams/breathing-at-high-altitude/hero.webpSix-step diagram of breathing at high altitude: lower air pressure, lower oxygen pressure, carotid body response, faster breathing, alkalosishttps://www.therespiratorysystem.com/assets/img/diagrams/breathing-at-high-altitude/oxygen-pressure-by-altitude.webpBar chart showing the inspired partial pressure of oxygen falling from sea level to the summit of Mount Everesthttps://www.therespiratorysystem.com/assets/img/diagrams/breathing-at-high-altitude/arrival-vs-acclimatized.webpComparison chart of breathing, blood carbon dioxide, pH, heart rate, red blood cells and exercise on arrival at altitude and after acclimatizationhttps://www.therespiratorysystem.com/assets/img/ai/breathing-at-high-altitude/highland-plateau.webpIllustration of a high-altitude village on a wide mountain plateau with snow-capped peaks behind it https://www.therespiratorysystem.com/breathing-vs-respiration/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/breathing-vs-respiration/hero-illustration.webpIllustration of a person standing on a hilltop at sunrise taking a slow deep breath of fresh morning airhttps://www.therespiratorysystem.com/assets/img/diagrams/breathing-vs-respiration/hero.webpComparison chart of breathing and cellular respiration showing process type, location, energy, gases and controlhttps://www.therespiratorysystem.com/assets/img/diagrams/breathing-vs-respiration/breath-to-energy.webpSix-step diagram from breathing to external respiration, gas transport, internal respiration, cellular respiration and carbon dioxide removalhttps://www.therespiratorysystem.com/assets/img/ai/breathing-vs-respiration/mitochondrion-energy.webpIllustration of a mitochondrion cut open inside a cell, showing folded inner membranes and glowing energy particles https://www.therespiratorysystem.com/glossary/choanae/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--choanae/hero-illustration.webpIllustration of a head cut in side view with the opening at the back of the nasal cavity glowing softlyhttps://www.therespiratorysystem.com/wp-content/uploads/2018/01/Choanae-Internal-Nares.jpgDiagram of the choanae (internal nares) at the back of the nasal cavity, opening into the nasopharynx on either side of the vomerhttps://www.therespiratorysystem.com/assets/img/ai/glossary--choanae/skull-base-choanae.webpIllustration of a skull seen from below with the two oval rear nasal openings separated by a thin midline bonehttps://www.therespiratorysystem.com/assets/img/ai/glossary--choanae/nose-breathing-hiker.webpIllustration of a hiker in profile breathing in calmly through the nose beside a mountain lake https://www.therespiratorysystem.com/cough-reflex/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/cough-reflex/hero-illustration.webpIllustration of a person coughing into the crook of the elbow on an autumn park pathhttps://www.therespiratorysystem.com/assets/img/diagrams/cough-reflex/hero.webpSix-step diagram of the cough reflex pathway from airway receptors through the vagus nerve and medulla to the breathing muscleshttps://www.therespiratorysystem.com/assets/img/diagrams/cough-reflex/cough-stages-cycle.webpCycle diagram of the stages of a cough: inspiratory, compressive, expulsive and relaxationhttps://www.therespiratorysystem.com/assets/img/diagrams/cough-reflex/cough-vs-gag.webpComparison chart of the cough reflex and the gag reflex, showing their purpose, trigger sites, nerves and actionshttps://www.therespiratorysystem.com/assets/img/ai/cough-reflex/cough-clearing-airway.webpIllustration of the windpipe cut open lengthwise with a clump of dust and mucus being pushed upward https://www.therespiratorysystem.com/respiratory-system-development/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-development/hero-illustration.webpIllustration of a pair of tiny fetal lungs with fine branching airways around a small hearthttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-development/hero.webpFive-stage diagram of lung development: embryonic, pseudoglandular, canalicular, saccular and alveolar stages with typical weekshttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-development/airway-branching-development.webpBranching diagram of airway development from the lung bud through bronchial, lobar and segmental buds to terminal bronchioles and alveolihttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-development/fetal-vs-newborn-lungs.webpComparison chart of fetal lungs and lungs after birth: contents, site of gas exchange, blood flow, shunts, vessels and breathinghttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-development/newborn-baby.webpIllustration of a newborn baby wrapped in a cream blanket sleeping peacefully in a crib https://www.therespiratorysystem.com/glossary/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary/hero-illustration.webpIllustration of a study desk with an open textbook and a small plastic lung modelhttps://www.therespiratorysystem.com/wp-content/themes/Respiratory/images/respiratory-system-diagram.jpgLabeled diagram of the human respiratory system with the nostrils, nasal cavity, pharynx, larynx, trachea, bronchi, lung lobes and diaphragmhttps://www.therespiratorysystem.com/wp-content/uploads/2017/11/Lung-Lobes.jpgDiagram of the lung lobes: superior, middle and inferior lobes of the right lung and superior and inferior lobes of the left lunghttps://www.therespiratorysystem.com/assets/img/ai/glossary/nose-throat-cutaway.webpIllustration of a side cutaway of the head showing the nasal cavity, mouth, throat and larynxhttps://www.therespiratorysystem.com/assets/img/ai/glossary/winter-breath.webpIllustration of a person in a wool hat breathing out a cloud of vapor in cold morning air https://www.therespiratorysystem.com/glossary/haldane-effect/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--haldane-effect/hero-illustration.webpIllustration of bright red blood cells in a lung capillary releasing gas across the thin wall of an alveolushttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--haldane-effect/hero.webpDiagram of the Haldane effect in the lungs: oxygen enters a red blood cell and binds hemoglobin, which releases carbon dioxidehttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--haldane-effect/haldane-effect-steps.webpSix-step diagram of the Haldane effect in the lungs, from oxygen binding hemoglobin to carbon dioxide leaving the bloodhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--haldane-effect/haldane-vs-bohr.webpComparison chart of the Haldane effect and the Bohr effect: what each describes, its signal, curve and role in the lungs and tissueshttps://www.therespiratorysystem.com/assets/img/ai/glossary--haldane-effect/tissue-capillary-co2.webpIllustration of dark red blood cells in a tissue capillary giving oxygen to cells and picking up carbon dioxide https://www.therespiratorysystem.com/glossary/hering-breuer-reflex/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--hering-breuer-reflex/hero-illustration.webpIllustration of inflated lungs with a glowing nerve running up from each lung to the brainstemhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--hering-breuer-reflex/hero.webpCycle diagram of the Hering-Breuer reflex: lung inflation, stretch receptors, vagus nerve, brainstem and exhalationhttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--hering-breuer-reflex/inflation-vs-deflation.webpComparison chart of the Hering-Breuer inflation reflex and deflation reflex: trigger, receptors, nerve and effecthttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--hering-breuer-reflex/infants-vs-adults.webpComparison chart of the Hering-Breuer reflex in newborns and adults: strength, when it acts and main rolehttps://www.therespiratorysystem.com/assets/img/ai/glossary--hering-breuer-reflex/sleeping-infant.webpIllustration of a newborn baby sleeping peacefully on its back in a crib under a soft blanket https://www.therespiratorysystem.com/how-do-lungs-work/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/how-do-lungs-work/hero-illustration.webpIllustration of a pair of fully inflated lungs with the windpipe and bronchi above a flattened diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/how-do-lungs-work/hero.webpEight-step diagram of how the lungs work: brain signal, diaphragm contraction, air in, cleaning, oxygen in, carbon dioxide out, heart, breath outhttps://www.therespiratorysystem.com/wp-content/uploads/2017/09/Lungs.jpgLabeled diagram of the lungs showing the trachea, primary bronchi, lobes, alveoli, pleura and diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/how-do-lungs-work/lungs-and-heart-loop.webpCycle diagram of how the lungs work with the heart: right heart, lungs, left heart, body tissues and veins back to the right hearthttps://www.therespiratorysystem.com/assets/img/ai/how-do-lungs-work/sleeping-person-breathing.webpIllustration of a person sleeping peacefully in bed while the chest rises gently with each breathhttps://www.therespiratorysystem.com/assets/img/ai/how-do-lungs-work/cough-into-elbow.webpIllustration of a person coughing lightly into the crook of the elbow in a bright room https://www.therespiratorysystem.com/exercise-and-the-respiratory-system/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/exercise-and-the-respiratory-system/hero-illustration.webpIllustration of a group of runners in mid-stride on a sunny track, breathing hardhttps://www.therespiratorysystem.com/assets/img/diagrams/exercise-and-the-respiratory-system/hero.webpSix-step diagram of how breathing responds to exercise, from anticipation and a fast rise at onset to steady state and recoveryhttps://www.therespiratorysystem.com/assets/img/diagrams/exercise-and-the-respiratory-system/rest-vs-exercise.webpComparison chart of breathing at rest and during hard exercise, including breath size, air per minute, exhalation and lung capillarieshttps://www.therespiratorysystem.com/assets/img/diagrams/exercise-and-the-respiratory-system/ventilation-by-activity.webpBar diagram showing how the volume of air breathed per minute increases from rest to walking, jogging, hard running and maximal efforthttps://www.therespiratorysystem.com/assets/img/ai/exercise-and-the-respiratory-system/swimmer-breathing.webpIllustration of a swimmer in a pool turning the head to the side to breathe in during freestyle https://www.therespiratorysystem.com/how-long-can-you-hold-your-breath/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/how-long-can-you-hold-your-breath/hero-illustration.webpIllustration of a freediver in a wetsuit and fins gliding calmly down a rope in clear deep blue waterhttps://www.therespiratorysystem.com/assets/img/diagrams/how-long-can-you-hold-your-breath/hero.webpSix-step diagram of a breath hold: breath stops, oxygen falls, carbon dioxide builds up, chemoreceptors fire, diaphragm contractions, breaking pointhttps://www.therespiratorysystem.com/assets/img/diagrams/how-long-can-you-hold-your-breath/land-vs-water.webpComparison of a breath hold on land and in water: diving reflex, heart rate, blood flow, oxygen use and what happens after faintinghttps://www.therespiratorysystem.com/assets/img/diagrams/how-long-can-you-hold-your-breath/humans-vs-diving-mammals.webpBar chart comparing the longest breath holds of an untrained adult, a record freediver, a sperm whale and a Cuvier's beaked whalehttps://www.therespiratorysystem.com/assets/img/ai/how-long-can-you-hold-your-breath/child-holding-breath.webpIllustration of a child with puffed cheeks playfully holding a breath against a bright wall https://www.therespiratorysystem.com/respiratory-system-homeostasis/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-homeostasis/hero-illustration.webpIllustration of the brain and brainstem glowing above the lungs with a nerve running down to the diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-homeostasis/hero.webpNegative feedback loop of breathing: rising CO2, chemoreceptors, brainstem, diaphragm and intercostals, faster breathing, balance restoredhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-homeostasis/too-slow-vs-too-fast.webpComparison of breathing too slowly and too fast: effect on blood carbon dioxide, pH, acid-base result, brainstem and kidney responsehttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-homeostasis/wall-thermostat.webpIllustration of a round smart thermostat on the wall of a cozy living room https://www.therespiratorysystem.com/respiratory-system-and-other-body-systems/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-system-and-other-body-systems/hero-illustration.webpIllustration of a young adult jogging along a park path in warm morning lighthttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-and-other-body-systems/hero.webpCycle diagram of how the muscular, nervous, respiratory and circulatory systems work together to control breathinghttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-and-other-body-systems/exercise-teamwork.webpFive-step diagram of how the muscular, nervous, respiratory and circulatory systems respond together during exercisehttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-system-and-other-body-systems/respiratory-vs-digestive.webpComparison chart of the respiratory system and the digestive system: jobs, shared pharynx, main tubes, organs and wasteshttps://www.therespiratorysystem.com/assets/img/ai/respiratory-system-and-other-body-systems/lungs-heart-vessels.webpIllustration of the heart in the center with blue and red blood vessels branching through both transparent lungs https://www.therespiratorysystem.com/how-to-make-a-lung-model/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/how-to-make-a-lung-model/hero-illustration.webpIllustration of a balloon lung model made from a plastic bottle on a classroom desk with a hand pulling the basehttps://www.therespiratorysystem.com/assets/img/diagrams/how-to-make-a-lung-model/hero.webpSix-step diagram of how to make a balloon lung model from a plastic bottle, small balloons, a Y-shaped straw, clay and a balloon diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/how-to-make-a-lung-model/model-vs-body.webpChart matching each part of the balloon lung model to the body: bottle and chest wall, straw and trachea, balloons and lungs, sheet and diaphragmhttps://www.therespiratorysystem.com/assets/img/diagrams/how-to-make-a-lung-model/how-the-model-breathes.webpCycle diagram of the balloon lung model: pulling the sheet lowers pressure and inflates the balloons, releasing it deflates themhttps://www.therespiratorysystem.com/assets/img/ai/how-to-make-a-lung-model/lung-model-materials.webpIllustration of a flat lay of a plastic bottle, balloons, a straw, scissors, tape and a rubber band for a lung model https://www.therespiratorysystem.com/hyperventilation-and-hypoventilation/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/hyperventilation-and-hypoventilation/hero-illustration.webpIllustration of a young woman pausing at the top of a staircase, breathing quickly after the climbhttps://www.therespiratorysystem.com/assets/img/diagrams/hyperventilation-and-hypoventilation/hero.webpComparison chart of hyperventilation and hypoventilation showing their effects on blood CO2, pH, oxygen and capnographyhttps://www.therespiratorysystem.com/assets/img/diagrams/hyperventilation-and-hypoventilation/co2-levels.webpBar chart comparing arterial carbon dioxide levels in hypoventilation, normal breathing and hyperventilationhttps://www.therespiratorysystem.com/assets/img/diagrams/hyperventilation-and-hypoventilation/co2-feedback-loop.webpCycle diagram of the carbon dioxide feedback loop that adjusts breathing through chemoreceptors and the brainstemhttps://www.therespiratorysystem.com/assets/img/ai/hyperventilation-and-hypoventilation/pulse-oximeter-fingertip.webpIllustration of a hand with a small pulse oximeter clip on the fingertip glowing with red light https://www.therespiratorysystem.com/inferior-nasal-concha/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/inferior-nasal-concha/hero-illustration.webpIllustration of the inside of the nasal cavity wall with the largest, lowest curled shelf, the inferior concha, highlightedhttps://www.therespiratorysystem.com/wp-content/uploads/2015/04/Inferior-Nasal-Concha.jpgFront view of the skull labeling the inferior nasal concha in the lower nasal opening beside the vomer, with nearby skull boneshttps://www.therespiratorysystem.com/assets/img/ai/inferior-nasal-concha/inferior-concha-bone.webpIllustration of the inferior nasal concha bone on its own, a thin curled scroll of ivory bonehttps://www.therespiratorysystem.com/assets/img/ai/inferior-nasal-concha/cold-air-breath.webpIllustration of a person in a winter scarf breathing in through the nose on a cold snowy morning https://www.therespiratorysystem.com/glossary/intercostal-muscles/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--intercostal-muscles/hero-illustration.webpIllustration of the rib cage with thin sheets of intercostal muscle filling the spaces between the ribshttps://www.therespiratorysystem.com/wp-content/uploads/2018/05/Intercostal-Muscles.jpgFront view of the rib cage showing the intercostal muscles between the ribs, with a close-up of the external, internal and innermost layershttps://www.therespiratorysystem.com/wp-content/uploads/2018/05/Intercostal-Muscles-Function.jpgRib cage during inhalation and exhalation: external intercostals lift the ribs as the diaphragm contracts, internal intercostals lower themhttps://www.therespiratorysystem.com/assets/img/ai/glossary--intercostal-muscles/neurovascular-bundle.webpIllustration of a vein, an artery and a nerve running together in the groove under a ribhttps://www.therespiratorysystem.com/assets/img/ai/glossary--intercostal-muscles/side-breathing.webpIllustration of a person sitting upright with hands on the sides of the ribcage as the chest widens during a breath in https://www.therespiratorysystem.com/glossary/lung-lobes/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--lung-lobes/hero-illustration.webpIllustration of the two lungs from the front with three lobes on the right and two on the left, separated by fissureshttps://www.therespiratorysystem.com/wp-content/uploads/2017/11/Lung-Lobes.jpgLabeled diagram of the lung lobes: right lung with superior, middle and inferior lobes, left lung with two lobes, fissures and cardiac notchhttps://www.therespiratorysystem.com/assets/img/ai/glossary--lung-lobes/right-lung-lateral.webpIllustration of the right lung from the side showing its three lobes divided by two fissureshttps://www.therespiratorysystem.com/assets/img/ai/glossary--lung-lobes/orange-segments.webpIllustration of a peeled orange split into wedge-shaped segments on a plate https://www.therespiratorysystem.com/middle-nasal-concha/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/middle-nasal-concha/hero-illustration.webpIllustration of a front cross-section of the nasal cavity showing the septum and three curled conchae on each side, with the middle concha highlightedhttps://www.therespiratorysystem.com/wp-content/uploads/2015/04/Middle-Nasal-Concha.jpgFront view of the skull labeling the middle nasal concha of the ethmoid bone between the superior and inferior nasal conchaehttps://www.therespiratorysystem.com/assets/img/ai/middle-nasal-concha/ethmoid-bone-concha.webpIllustration of the ethmoid bone on its own with a thin curled middle nasal concha hanging from each sidehttps://www.therespiratorysystem.com/assets/img/ai/middle-nasal-concha/three-conchae-stack.webpIllustration of the three nasal conchae stacked from small at the top to large at the bottom https://www.therespiratorysystem.com/nasal-conchae-nasal-turbinates/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/nasal-conchae-nasal-turbinates/hero-illustration.webpIllustration of the inner wall of the nose showing three stacked curled shelves covered in rosy lininghttps://www.therespiratorysystem.com/wp-content/uploads/2015/04/Nasal-Conchae.jpgLabeled side view of the nasal cavity and front view of the skull showing the superior, middle and inferior nasal conchaehttps://www.therespiratorysystem.com/wp-content/uploads/2015/04/Nasal-Turbinates.jpgCoronal section of the nose showing the superior, middle and inferior turbinates, the meatuses below them, the septum and sinuseshttps://www.therespiratorysystem.com/assets/img/ai/nasal-conchae-nasal-turbinates/nasal-cavity-front-section.webpIllustration of a slice through the nose seen from the front with curled shelves jutting in from both side wallshttps://www.therespiratorysystem.com/assets/img/ai/nasal-conchae-nasal-turbinates/spring-meadow-pollen.webpIllustration of a person breathing in through the nose in a blooming spring meadow full of floating pollen https://www.therespiratorysystem.com/nasal-meatus/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/nasal-meatus/hero-illustration.webpIllustration of the nasal cavity wall with three curled shelves and the shadowed channels beneath each, with a thin trail of mucus draininghttps://www.therespiratorysystem.com/wp-content/uploads/2015/04/Nasal-Meatus-Anatomy.jpgFront cross-section of the nose labeling the superior, middle and inferior meatuses beneath the matching nasal conchae on both sideshttps://www.therespiratorysystem.com/wp-content/uploads/2015/04/Nasal-Meatus.jpgSide view of the lateral nasal wall showing the meatuses with the sinus openings, semilunar hiatus and nasolacrimal duct opening labeledhttps://www.therespiratorysystem.com/assets/img/ai/nasal-meatus/tear-drainage.webpIllustration of a close-up of an eye with a single tear drop at the inner corner near the nosehttps://www.therespiratorysystem.com/assets/img/ai/nasal-meatus/blowing-nose.webpIllustration of a person in a cozy sweater gently blowing their nose into a tissue https://www.therespiratorysystem.com/glossary/nasal-vestibule/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--nasal-vestibule/hero-illustration.webpIllustration of a close-up nostril entrance lined with short stiff hairshttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--nasal-vestibule/hero.webpFive-step diagram of air entering the nose: nostril, nasal vestibule, limen nasi, internal nasal valve and nasal cavity properhttps://www.therespiratorysystem.com/wp-content/uploads/2018/01/Nostrils-Anatomy.jpgSide and underside views of the nose showing the nostrils and the lateral and medial crura of the major alar cartilagehttps://www.therespiratorysystem.com/assets/img/diagrams/glossary--nasal-vestibule/vestibule-vs-respiratory-region.webpComparison chart of the nasal vestibule and the respiratory region of the nasal cavity: lining, hairs, glands and functionhttps://www.therespiratorysystem.com/assets/img/ai/glossary--nasal-vestibule/vestibule-cutaway.webpIllustration of a nose cut in side view showing the small hairy chamber just inside the nostrilhttps://www.therespiratorysystem.com/assets/img/ai/glossary--nasal-vestibule/cold-morning-breath.webpIllustration of a person in a scarf walking in a snowy park, breathing in cold air through the nose https://www.therespiratorysystem.com/glossary/nasopharynx/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--nasopharynx/hero-illustration.webpIllustration of a head in side cutaway with the nasopharynx highlighted behind the nasal cavity above the soft palatehttps://www.therespiratorysystem.com/wp-content/uploads/2018/02/Nasopharynx.jpgSide view of the head showing the nasopharynx behind the nasal cavity, with the adenoids, Eustachian tube opening and soft palatehttps://www.therespiratorysystem.com/assets/img/ai/glossary--nasopharynx/nasopharynx-interior.webpIllustration of the inside of the nasopharynx with the adenoid pad on the roof and the openings of the auditory tubes on the side wallshttps://www.therespiratorysystem.com/assets/img/ai/glossary--nasopharynx/airplane-ear-pressure.webpIllustration of a calm airplane passenger by the window sipping water from a small cup to even out ear pressure https://www.therespiratorysystem.com/nose-vs-mouth-breathing/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/nose-vs-mouth-breathing/hero-illustration.webpIllustration of a person jogging on a forest trail in the cool morning breathing through the mouthhttps://www.therespiratorysystem.com/assets/img/diagrams/nose-vs-mouth-breathing/hero.webpComparison chart of nose breathing vs mouth breathing: filtering, warming, humidifying, resistance, nitric oxide, smell and best usehttps://www.therespiratorysystem.com/assets/img/diagrams/nose-vs-mouth-breathing/how-the-nose-conditions-air.webpSix-step diagram of how the nose filters, warms and humidifies air from the nostrils to the nasopharynxhttps://www.therespiratorysystem.com/wp-content/uploads/2015/12/Upper-Respiratory-Tract.jpgSide view of the head showing the nasal cavity and oral cavity both opening into the pharynx above the larynx and tracheahttps://www.therespiratorysystem.com/assets/img/ai/nose-vs-mouth-breathing/sleeping-nose-breathing.webpIllustration of a person asleep on the back in bed with the mouth closed, breathing quietly through the nosehttps://www.therespiratorysystem.com/assets/img/ai/nose-vs-mouth-breathing/skull-airways.webpIllustration of a human skull from the side showing the nasal opening, the upper jaw and the lower jaw https://www.therespiratorysystem.com/glossary/nostrils/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--nostrils/hero-illustration.webpIllustration of the underside of a human nose showing two rounded nostril openingshttps://www.therespiratorysystem.com/wp-content/uploads/2018/01/Nostrils-Anatomy.jpgLabeled diagram of the nostrils (external nares) on the underside of the nose, with the ala, columella and nasal septumhttps://www.therespiratorysystem.com/assets/img/ai/glossary--nostrils/smelling-flower.webpIllustration of a person in profile smelling a pink flower in a sunny gardenhttps://www.therespiratorysystem.com/assets/img/ai/glossary--nostrils/nasal-passages-top-view.webpIllustration of a horizontal slice through the nose showing two separate air passages divided by a thin midline wall https://www.therespiratorysystem.com/glossary/oral-cavity/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/glossary--oral-cavity/hero-illustration.webpIllustration of an open mouth seen from the front showing the teeth, tongue, palate and uvulahttps://www.therespiratorysystem.com/wp-content/uploads/2018/04/Oral-Cavity.jpgFront view of the open mouth labeling the lips, gums, teeth, hard and soft palate, uvula, tongue, frenula and submandibular duct openinghttps://www.therespiratorysystem.com/wp-content/uploads/2018/04/Oral-Cavity-Anatomy-Diagram.jpgSide view of the head showing the oral vestibule, oral cavity proper, hard and soft palate, uvula, tongue and oropharynx below the nasal cavityhttps://www.therespiratorysystem.com/assets/img/ai/glossary--oral-cavity/salivary-glands.webpIllustration of a head from the side with the main salivary glands near the ear and under the jaw highlightedhttps://www.therespiratorysystem.com/assets/img/ai/glossary--oral-cavity/person-eating.webpIllustration of a person at a table chewing a forkful of pasta from a bowl https://www.therespiratorysystem.com/partial-pressure-of-gases/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/partial-pressure-of-gases/hero-illustration.webpIllustration of a glass flask holding a mixture of pale grey, sky-blue and dark grey gas moleculeshttps://www.therespiratorysystem.com/assets/img/diagrams/partial-pressure-of-gases/hero.webpSix-step diagram of the oxygen cascade: PO2 falls from about 160 mmHg in air to 150, 100, 95 to 100, 40 and a few mmHg in cellshttps://www.therespiratorysystem.com/assets/img/diagrams/partial-pressure-of-gases/dalton-air-partial-pressures.webpBar chart of partial pressures in dry air at sea level: nitrogen largest, oxygen about a fifth, argon small, carbon dioxide a tracehttps://www.therespiratorysystem.com/assets/img/diagrams/partial-pressure-of-gases/pao2-vs-sao2.webpComparison chart of partial pressure of oxygen (PaO2) and oxygen saturation: what each measures, units, normal values and how they relatehttps://www.therespiratorysystem.com/assets/img/ai/partial-pressure-of-gases/scuba-diver.webpIllustration of a scuba diver with a tank floating above a coral reef in clear blue water https://www.therespiratorysystem.com/pleural-cavity/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/pleural-cavity/hero-illustration.webpIllustration of a slice through the lung edge and chest wall showing a thin glossy double membrane with a film of fluid between the layershttps://www.therespiratorysystem.com/assets/img/diagrams/pleural-cavity/hero.webpCycle diagram of pleural fluid turnover: filtration from parietal pleura capillaries, a thin film, downward flow, stomata and lymphatic drainagehttps://www.therespiratorysystem.com/assets/img/diagrams/pleural-cavity/pressure-during-a-breath.webpSix-step diagram of how pressure in the pleural cavity changes during one quiet breath in and outhttps://www.therespiratorysystem.com/assets/img/diagrams/pleural-cavity/pleura-vs-pleural-cavity.webpComparison chart of the pleura, the membrane around the lung, and the pleural cavity, the fluid-filled space between its layershttps://www.therespiratorysystem.com/assets/img/ai/pleural-cavity/glass-slides-water.webpIllustration of two glass slides pressed together with a thin film of water between them, sliding sideways but hard to pull apart https://www.therespiratorysystem.com/respiratory-rate/2026-11-02https://www.therespiratorysystem.com/assets/img/ai/respiratory-rate/hero-illustration.webpIllustration of a sleeping baby in a crib under a soft blanket with the tummy gently risinghttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-rate/hero.webpCycle diagram of breathing rate control: brainstem rhythm, nerves, breathing muscles, blood gas change and chemoreceptor feedbackhttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-rate/breathing-rate-by-age.webpBar chart showing typical resting breathing rate highest in newborns and falling steadily through childhood to the adult rangehttps://www.therespiratorysystem.com/assets/img/diagrams/respiratory-rate/respiratory-rate-vs-heart-rate.webpComparison chart of respiratory rate and heart rate: what each counts, typical adult values, pacemaker, muscle and 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