The Respiratory SystemCh 22

Human AnatomySonya Schuh-Huerta, Ph.D.Leonardo Da Vinci

The Upper Respiratory TractSphenoid sinusFrontal sinusNasal meatuses(superior, middle,and inferior)NasopharynxUvulaPalatine tonsilIsthmus of thefaucesPosterior nasalapertureOpening ofpharyngotympanictubePharyngeal tonsilOropharynxLaryngopharynxVocal foldEsophagusNasal conchae(superior, middle and inferior)Nasal vestibuleNostrilNasal cavityHard palateSoft palateTongueLingual tonsilEpiglottisHyoid boneLarynxThyroid cartilageVestibular foldCricoid cartilageThyroid glandTracheaCribriform plateof ethmoid bone

Organs of the Respiratory SystemNasal cavityTracheaCarina of tracheaLeft main (primary) bronchusRight main (primary) bronchusRight lungParietalpleuraLeft lungAlveoliBronchiNostrilOral cavityPharynxLarynxDiaphragm

Bronchi in the Conducting ZoneTracheaSuperior lobe of right lungMiddle lobe of right lungInferior lobe of right lungSuperior lobe of left lungLeft main(primary) bronchusLobar(secondary)bronchusSegmental(tertiary)bronchusInferior lobeof left lung(a) The branching of the bronchial tree

Structures of the Respiratory Zone

Alveoli & the Respiratory MembraneElasticfibers(a) Diagrammatic view of capillary-alveoli relationshipsSmoothmuscleAlveolusCapillariesTerminal bronchioleRespiratory bronchiole

Anatomy of Alveoli & the Respiratory MembraneAlveolusCapillaryType II (surfactant-secreting) cellType I cell of alveolar wallEndothelial cell nucleusMacrophageAlveoli (gas-filledair spaces)Red blood cellin capillaryAlveolar poresCapillary endotheliumFused basement membranes of the alveolar epitheliumand the capillary endotheliumAlveolar epitheliumRespiratorymembraneRed blood cellO2AlveolusCO2CapillaryNucleus of type I(squamousepithelial) cell(c) Detailed anatomy of the respiratory membrane

The Respiratory SystemBasic functions of the respiratory systemSupplies body with oxygenDisposes of carbon dioxide4 processes involved in respiration:Pulmonary ventilationExternal respirationTransport of respiratory gasesInternal respiration

Functional Anatomy of the Respiratory SystemRespiratory organsNose, nasal cavity, & paranasal sinusesPharynx, larynx, & tracheaBronchi & smaller branchesLungs & alveoli

Organs of the Respiratory SystemDivided intoConducting zoneRespiratory zone

The NoseProvides an airway for respirationMoistens & warms air (humidifies air)Filters inhaled airResonating chamber for speechHouses olfactory receptors (olfaction)

The NoseSize variation due to differences in nasal cartilagesSkin is thin contains many sebaceous glands

The Nasal CavityExternal nares nostrilsDivided by nasal septumContinuous with nasopharynx

Nasal Cavity2 types of mucous membrane:Olfactory mucosaNear roof of nasal cavityHouses olfactory receptorsRespiratory mucosaLines nasal cavityPseudostratified ciliated columnar epithelium

The Upper Respiratory TractSphenoid sinusFrontal sinusNasal meatuses(superior, middle,and inferior)NasopharynxUvulaPalatine tonsilIsthmus of thefaucesPosterior nasalapertureOpening ofpharyngotympanictubePharyngeal tonsilOropharynxLaryngopharynxVocal foldEsophagusNasal conchae(superior, middle and inferior)Nasal vestibuleNostrilNasal cavityHard palateSoft palateTongueLingual tonsilEpiglottisHyoid boneLarynxThyroid cartilageVestibular foldCricoid cartilageThyroid glandTracheaCribriform plateof ethmoid bone

Respiratory MucosaConsists of:Pseudostratified ciliated columnar epitheliumGoblet cells within epithelium Underlying layer of lamina propria Cilia move contaminated mucus posteriorly

Nasal ConchaeSuperior & middle nasal conchae Part of the ethmoid boneInferior nasal conchaeSeparate boneProject medially from the lateral wall of the nasal cavityParticulate matter: Deflected to mucus-coated surfaces

The PharynxFunnel-shaped passagewayConnects nasal cavity & mouthDivided into 3 sections by location:NasopharynxOropharynxLaryngopharynx Type of mucosal lining changes along its length

The NasopharynxSuperior to the point where food entersOnly an air passagewayClosed off during swallowingPharyngeal tonsil (adenoids) Located on posterior wallDestroys pathogens that enter Contains the opening to the pharyngotympanic tube (auditory or eustachian tube)Tubal tonsilProvides some protection from infection

The OropharynxArch-like entrance-way faucesExtends from soft palate to epiglottisEpitheliumStratified squamous epithelium2 types of tonsils in the oropharynxPalatine tonsils in lateral walls of the fauces Lingual tonsils covers the posterior surface of the tongue

The LaryngopharynxPassageway for both food & airEpitheliumStratified squamous epitheliumContinuous with the esophagus & larynx

The Larynx3 functions Voice productionProvides an open airwayRoutes air & food into the proper channelsSuperior opening (epiglotis) is:Closed during swallowingOpen during breathing

9 Cartilages of the LarynxThyroid cartilageShield-shaped, forms laryngeal prominence (= Adams apple)3 pairs of small cartilagesArytenoid cartilagesCorniculate cartilagesCuneiform cartilagesEpiglottisTips inferiorly during swallowing

The LarynxVocal ligaments of the larynxVocal folds (= true vocal cords)Function in sound productionVestibular folds (= false vocal cords)No role in sound productionEpithelium of the larynx:Stratified squamous superior portionPseudostratified ciliated columnar inferior portion

Anatomy of the LarynxBody of hyoid boneCricoid cartilageLaryngeal prominence(Adams apple)ClavicleSternal headClavicular headSternocleidomastoidJugular notch(a) Surface viewBody of hyoid boneEpiglottisCricoid cartilageTrachealcartilagesThyroid cartilageLaryngeal prominence(Adams apple)Cricothyroid ligamentCricotracheal ligament(b) Anterior viewThyrohyoidmembrane

Anatomy of the LarynxHyoid boneThyroidcartilageGlottis(c) Photograph of cartilaginous framework of the larynx, posterior viewEpiglottisCorniculate cartilageArytenoid cartilageCricoid cartilageTracheal cartilagesThyrohyoidmembraneEpiglottisBody of hyoid boneThyrohyoid membraneVestibular fold(false vocal cord)Vocal fold(true vocal cord)Cricothyroid ligamentCricotracheal ligamentFatty padThyroid cartilageCuneiform cartilageCorniculate cartilageArytenoid cartilageCricoid cartilageTracheal cartilagesArytenoid muscle(d) Sagittal section (anterior on the right)Thyrohyoidmembrane

Movements of the Vocal Cords(a) Vocal folds in closed position; closed glottis(b) Vocal folds in open position; open glottisBase of tongueEpiglottisVestibular fold (false vocal cord)Vocal fold (true vocal cord)GlottisInner lining of tracheaCuneiform cartilageCorniculate cartilageThyroid cartilageCricoid cartilageVocal ligaments of vocal cordsLateral cricoarytenoid muscleArytenoid cartilagePosterior cricoarytenoid muscleAnteriorPosteriorGlottisCorniculate cartilage

The LarynxVoice production Length of the vocal folds changes with pitchLoudness depends on the force of air across the vocal foldsSphincter function of the larynxValsalvas maneuver straining Innervation of the larynxRecurrent laryngeal nerves (branch of vagus)

The TracheaDescends into the mediastinumC-shaped cartilage rings keep airway open!CarinaMarks where trachea divides into 2 primary bronchiEpithelium Pseudostratified ciliated columnar epithelium ~remember this?

The Trachea(a) Cross section of the trachea and esophagusHyaline cartilageSubmucosaMucosaSeromucous glandin submucosaPosteriorLumen of tracheaAnteriorEsophagusTrachealismuscleAdventitia(b) Photomicrograph of the tracheal wall (250)Hyaline cartilageLamina propria(connective tissue)SubmucosaMucosaSeromucous glandin submucosaPseudostratifiedciliated columnarepithelium

Bronchi in the Conducting ZoneBronchial treeExtensively branching respiratory passagewaysPrimary bronchi (main bronchi)Largest bronchi Right main primary bronchiWider & shorter than the leftRight lung also bigger than the left

Bronchi in the Conducting ZoneTracheaSuperior lobe of right lungMiddle lobe of right lungInferior lobe of right lungSuperior lobe of left lungLeft main(primary) bronchusLobar(secondary)bronchusSegmental(tertiary)bronchusInferior lobeof left lung(a) The branching of the bronchial tree

Bronchi in the Conducting ZoneSecondary (lobar) bronchi Three on the right Two on the leftTertiary (segmental) bronchi Branch into each lung segmentBronchiolesLittle bronchi, less than 1 mm in diameterTerminal bronchiolesLess than 0.5 mm in diameter

Bronchi in the Conducting ZoneMucosa Pseudostratified epithelium Lamina propriaFibromusculo-cartilaginous layer Cartilage plate Smooth muscleLumen(b) Photomicrograph of a bronchus (13)

Changes in Tissue Along Conducting PathwaysSupportive connective tissues changeC-shaped rings replaced by cartilage platesEpithelium changesFirst, pseudostratified ciliated columnarReplaced by simple columnar, then simple cuboidal epitheliumSmooth muscle becomes important:Airways widen with sympathetic stimulationAirways constrict with parasympathetic stim.

Structures of the Respiratory ZoneConsists of air-exchanging structuresRespiratory bronchioles branch from terminal bronchiolesLead to alveolar ductsLead to alveolar sacs

Structures of the Respiratory Zone

Structures of the Respiratory Zone

Structures of the Respiratory ZoneAlveoli~300 million alveoli account for tremendous surface area of the lungs!Surface area of alveoli is ~140 square meters!!!Why such a large surface area?

Structures of the Respiratory ZoneStructure of alveoliType I cells single layer of simple squamous epithelial cellsSurrounded by basal laminaAlveolar & capillary walls plus their basal lamina formThe Respiratory membrane

Anatomy of Alveoli & the Respiratory MembraneElasticfibers(a) Diagrammatic view of capillary-alveoli relationshipsSmoothmuscleAlveolusCapillariesTerminal bronchioleRespiratory bronchiole

Structures of the Respiratory ZoneStructures of alveoli (cont.)Type II cells scattered among type I cellsAre cuboidal epithelial cellsSecrete surfactant (very important!)Detergent-like molecule, that reduces surface tension within alveoli (prevents them from collapsing)Alveolar macrophages also present

Anatomy of Alveoli & the Respiratory MembraneAlveolusCapillaryType II (surfactant-secreting) cellType I cell of alveolar wallEndothelial cell nucleusMacrophageAlveoli (gas-filledair spaces)Red blood cellin capillaryAlveolar poresCapillary endotheliumFused basement membranes of the alveolar epitheliumand the capillary endotheliumAlveolar epitheliumRespiratorymembraneRed blood cellO2AlveolusCO2CapillaryNucleus of type I(squamousepithelial) cell(c) Detailed anatomy of the respiratory membrane

The Respiratory ZoneFeatures of alveoliSurrounded by elastic fibersInterconnect by way of alveolar poresInternal surfaces A site for free movement of alveolar macrophages

Gross Anatomy of the LungsMajor landmarks of the lungsApex, base, hilum, & rootLeft lungSuperior & inferior lobesRight lungSuperior, middle, & inferior lobes

Leftsuperior lobeObliquefissureLeft inferiorlobe(b) Photograph of medial view of the left lung Left mainbronchusPulmonaryveinImpressionof heartObliquefissureLobulesPulmonary arteryApex of lungHilumAorticimpressionGross Anatomy of the LungsAnterior View of Thoracic StructuresTracheaApex of lungThymusRight superior lobeHorizontal fissureRight middle lobeOblique fissureRight inferior lobeHeart(in mediastinum)DiaphragmBase of lungLeftsuperior lobeCardiac notchObliquefissureLeft inferiorlobeLungPleural cavityParietal pleuraRibIntercostal muscleVisceral pleura(a) Anterior view. The lungs flank mediastinal structures laterally.

Bronchial TreeRightsuperiorlobe (3segments)Rightmiddlelobe (2segments)Rightinferior lobe(5 segments)Left superiorlobe(4 segments)Left inferiorlobe(5 segments)Right lungLeft lung

Blood Supply & Innervation of the LungsPulmonary arteriesDeliver oxygen-poor blood to the lungsPulmonary veinsCarry oxygenated blood to the heartInnervationSympathetic, parasympathetic, & visceral sensory fibersParasympathetic constrict airwaysSympathetic dilate airways

Transverse Cut Through Lungs(d) Transverse section through the thorax, viewed from above. Lungs, pleural membranes, and major organs in the mediastinum are shown.Esophagus(in mediastinum)Right lungParietal pleuraVisceral pleuraPleural cavityPericardial membranesSternumAnteriorPosteriorVertebraRoot of lungat hilumLeft lungThoracic wallPulmonary trunkHeart (in mediastinum)Anterior mediastinumLeft main bronchusLeft pulmonary arteryLeft pulmonary vein

The Pleurae (review)A double-layered sac surrounding each lungParietal pleuraVisceral pleuraPleural cavity Potential space between the visceral & parietal pleuraePleurae help divide the thoracic cavity Central mediastinum 2 lateral pleural compartments

Diagram of the Pleurae & Pleural CavitiesTracheaApex of lungThymusRight superior lobeHorizontal fissureRight middle lobeOblique fissureRight inferior lobeHeart(in mediastinum)DiaphragmBase of lungLeftsuperior lobeCardiac notchObliquefissureLeft inferiorlobeLungPleural cavityParietal pleuraRibIntercostal muscleVisceral pleura(a) Anterior view. The lungs flank mediastinal structures laterally.

The Mechanisms of Ventilation2 phases of pulmonary ventilationInspiration inhalation Expiration exhalation

InspirationVolume of thoracic cavity increasesDecreases internal gas pressureAction of the diaphragm Diaphragm flattensAction of intercostal musclesContraction raises the ribs

InspirationDeep inspiration requires ScalenesSternocleidomastoidPectoralis minorErector spinae extends the back

ExpirationQuiet expiration chiefly a passive process!Inspiratory muscles relaxDiaphragm moves superiorlyVolume of thoracic cavity decreasesForced expiration an active processProduced by contraction ofInternal & external oblique musclesTransverse abdominis muscles

Changes in Thoracic Volume

At rest, no air movement: Air pressure in lungs is equal to atmospheric (air) pressure. Pressure in the pleural cavity is less than pressure in the lungs. This pressure difference keeps the lungs inflated. Inspiration: Inspiratory muscles contract and increase the volume of the thoracic and pleural cavities. Pleural fluid in the pleural cavity holds the parietal and visceral pleura close together, causing the lungs to expand. As volume increases, pressure decreases and air flows into the lungs. Expiration: Inspiratory muscles relax, reducing thoracic volume, and the lungs recoil. Simultaneously, volumes of the pleural cavity and the lungs decrease, causing pressure to increase in the lungs, and air flows out. Resting state is reestablished.TracheaDiaphragmLungLungAir flows inAir flowsoutVPVPVPVPPleuralcavityThoracicwallAirAirMain bronchiParietalpleuraVisceralpleuraThoracic wallPleural cavityAt restExpanded123Changes in Thoracic Volume

Neural Control of VentilationRespiratory centerGenerates baseline respiration rateIn the reticular formation of the medulla oblongataChemoreceptorsSensitive to rising & falling oxygen levels Central chemoreceptors located in medullaPeripheral chemoreceptors Aortic bodies Carotid bodies

Location of Peripheral Chemoreceptors

Disorders of Lower Respiratory StructuresBronchial asthma A type of allergic inflammationHypersensitivity to irritants in the air or to stressAsthma attacks characterized byContraction of bronchiole smooth muscle Secretion of mucus in airways

Disorders of Lower Respiratory StructuresCystic fibrosis (CF) inherited disease Exocrine gland function is disruptedRespiratory system affected byOversecretion of viscous mucus Pneumonia infectious diseaseAccumulation of fluid in alveoliInterferes with gas exchange (drowning)

Disorders of Lower Respiratory StructuresChronic obstructive pulmonary disease (COPD)Airflow into & out of the lungs is difficultObstructive emphysemaChronic bronchitisHistory of smoking usually associated

Disorders of Lower Respiratory StructuresFigure 22.18

Alveolar Changes with EmphysemaFigure 22.19

Lung CancerMost common cause of cancer-related death! 1.3 million deaths/year worldwideTreated by surgery, radiation, and/or chemotherapySymptoms shortness of breath, coughing (up blood), weight loss History of smoking or 2nd- hand smoke usually associated14% survival rates

Aging of the Respiratory SystemThe number of glands in nasal mucosa declinesNose driesProduces thickened mucusThoracic wall becomes more rigidLungs lose elasticityOxygen levels in the blood may fall

AgainExercise throughout life is important for respiratory health!

Questions?

Whats Next?Tonights Lab: Lab Exam 4! Wed Lecture: Lecture Exam 4! Wed Lab: Start Digestive System