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Respiratory SystemFunctions of Respiratory SystemWhy We BreatheOrgans of the Respiratory SystemUpper Respiratory TractSlide 6Mucous MembranesSlide 8Slide 9Lower Respiratory TractCartilage of LarynxVocal CordsSlide 13Slide 14TracheaSlide 16Bronchial TreeSlide 18Composition of BronchiAlveoliSlide 21Boundaries of LungsPleural MembranesBreathingVolume vs. PressureSlide 26InspirationSlide 28Surface TensionExpirationSlide 31Respiratory VolumesSlide 33Respiratory CapacitiesSlide 35Nonrespiratory Air MovementRespiratory CenterFactors Affecting BreathingSlide 39Slide 40Inflation ReflexVoluntary Control of BreathingGas ExchangeTransport of OxygenCarbon MonoxideCarbon Dioxide TransportSuggested Homework QuestionsRESPIRATORY SYSTEMChapter 19FUNCTIONS OF RESPIRATORY SYSTEMFilter incoming airTransport air into lungsRespirationGas exchangeLevels of respirationVentilationExternal respirationInternal respirationCellular respirationWHY WE BREATHECellular respiration Cells derive energy from nutrients (e.g. glucose)Aerobic respiration Requires oxygen as final electron acceptorWaste products – CO2 and H2OWithout O2, aerobic respiration cannot proceedWithout removal of CO2, blood pH is disruptedORGANS OF THE RESPIRATORY SYSTEMUpper tractNoseNasal cavitySinusesPharynx Lower tractLarynxTracheaBronchusLungsUPPER RESPIRATORY TRACTNoseMuscle, bone, cartilageExternal nares (nostrils)Air enters tractHairs filter large particlesUPPER RESPIRATORY TRACTNasal cavityHollow space behind noseBoundaries: Ethmoid bone; hard palateNasal conchaeDivide cavity into passagesMeatuses (superior, middle, inferior)Support mucous membranesMUCOUS MEMBRANESLine nasal cavityPseudostratified ciliated epitheliumGoblet cellsSecrete mucusWarms and moistens airTraps dust, microbesCilia propel mucus and particles into pharynx to be swallowedUPPER RESPIRATORY TRACTSinusesAir-filled cavities, empty into nasal cavityFrontal, ethmoid, sphenoid, maxillaryLined with mucous membranes, drain into nasal cavityInflammation of membranes  block drainage, accumulate pressure  headacheUPPER RESPIRATORY TRACTPharynxPosterior to oral cavityBetween nasal cavity and larynxPassage for food and airDivisions NasopharynxOropharynxLaryngopharynxLOWER RESPIRATORY TRACTLarynxAKA Voice-boxSuperior to trachea, inferior to pharynxConsists of muscle and cartilageFunctions Block foreign objects from tracheaHouse vocal cordsCARTILAGE OF LARYNXThyroidCovered by thyroidProtrudes (Adam’s apple)CricoidInferior to thyroid cartilageEpiglottic Elastic cartilageConnected to thyroid cartilage Supports epiglottisVOCAL CORDSTwo folds within larynxUpper foldsMuscle + CTFalse vocal cordsDo not produce soundLower foldsElastic fibersTrue vocal cordsVocal sounds when fibers vibrateAlter tension  change pitchAlter intensity  change volumeVOCAL CORDSGlottisOpening between vocal cordsOpen during breathing (b)Close during swallowing (a)EpiglottisFlap that closes over larynx to prevent liquids/foods from entering larynxLOWER RESPIRATORY TRACTTracheaWindpipeCylindrical tubeFlexibleAnterior to esophagusSplits into bronchiTRACHEAInner wallCiliated epithelial cellsCilia filter incoming airMucous membraneGoblet cells  mucusTrap debrisOuter wallAnterior “C” shaped cartilaginous ringsPrevent collapsePosterior Smooth muscleAllow esophagus to expandLOWER RESPIRATORY TRACTBronchial treeAirways leading from trachea into lungsTrachea splits into primary bronchi (R&L)Carina – cartilage separating each bronchusBRONCHIAL TREEPrimary bronchiSecondary bronchiTertiary bronchiIntralobular bronchiolesTerminal bronchiolesBRONCHIAL TREERespiratory bronchiolesAlveolar ductsAlveolar sacsAlveoliCOMPOSITION OF BRONCHISimilar to tracheaCartilaginous rings replaced by “plates” in lungAmount of cartilage decreases with diminishing size of passagesSmooth muscle and elastic fibersCell typePseudostratified ciliated columnar (larger tubes)Cuboidal epithelium (bronchioles)Squamous epithelium (alveoli)ALVEOLIThin layer of epithelial cellsLarge surface area for gas exchangeO2 diffuses from alveolus into blood in capillaryCO2 diffuses from blood in capillary into alveolusLOWER RESPIRATORY TRACTLungsSoft, spongyRight lung – 3 lobesLeft lung – 2 lobesLobes  lobulesTerminal bronchioles + alveolar ducts, alveolar sacs, alveoli, nerves, blood vessels, lymphatic vesselsBOUNDARIES OF LUNGSThoracic cageRibs SternumDiaphragmHeartPLEURAL MEMBRANESVisceral pleuraParietal pleuraPleural cavityBREATHINGAlso called ventilationInspirationExpirationAtmospheric pressureWeight of air is force that moves air into lungs760 mm/Hg or 1 atmPressure exerted on all surfaces in contact with airPressure inside lungs is same as on outsideVOLUME VS. PRESSUREAIncrease volume, decrease air pressure inside pushing outside air inBDecrease volume, increases air pressure forcing air outVOLUME VS. PRESSURENormal inspirationPressure inside lung decreases, outside air pushed into airwaysINSPIRATIONDiaphragm stimulated by phrenic nerveDiaphragm , enlarging thoracic cavityIntra-alveolar pressure , forcing air into lungsINSPIRATIONExternal intercostal muscles raise ribs and elevate sternumLowers intra-alveolar pressure even more, causing more air to enterSURFACE TENSIONPleural membranesHelp expand lungs via surface tensionAlveoliSecrete surfactant to decrease surface tension to prevent alveolar collapseSurfactantSurface active agentEXPIRATIONElastic recoilElastic tissues of the lungs are stretched during inspiration; return to original state during expirationPressure between alveoli increases, forces air outEXPIRATIONPassive process Does not require muscle contractionForceful expirationIncrease pressure in lungs/abdominal cavity forcing air out of lungsInternal intercostalsInternal/external obliquesTransverse/rectus abdominisRESPIRATORY VOLUMESSpirometryMeasurement of air volumes in/out of lungsRespiratory cycleI + E; 13/minRESPIRATORY VOLUMESRespiratory

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