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• LECTURE7: Knowallthecomponentsoftherespiratorysystem andtheirmajorfunctions WeneedtotransferO2fromtheatmosphere toourtissuesandCO2fromthetissuesinto theatmosphere. Respiratorysystemalso: • AssistspHhomeostasis • Producesvocalsounds • Filtersairandprovidesforasenseof smell • Assistsregulationofheatandwater Theupperrespiratorysystemincludes: • Pharynx • Nose Thelowerrespiratorysystemincludes: • Larynx • Trachea • Rightmainbronchus • Lungs Principalorgansoftherespiratorysystem: • Nose-producesmucus,filters,warmsandmoistensincomingair • Paranasalsinuses-sameasnose.Mucosa-lined,airfilledcavities. • Pharynx-passageforairandfood.Connectsnasalcavitytolarynxandoralcavityto esophagus.Has3subdivisions:nasopharynx, oropharynx,andlaryngopharynx.Thenasopharynx helpswarmandhumidifyandfiltertheair. • Larynx-airpassageway;preventsfoodfromentering lowerrespiratorytract.Itprotectstheglottis(large cartilages)andproducessound(smallcartilage structuresandvocalfolds).Thereare3largecartilages: thyroid,cricoidcartilageandepiglottis. • Trachea-airpassageway;cleans,warmsandmoistens incomingair • Bronchialtree-airpassagewayconnectingtracheawith alveoli;cleans,warmsandmoistensincomingair.The bronchicontainincompleteringsofcartilageandare linedbypseudostratifiedciliatedcolumnarepithelium. Consistsofrightandleftmainbronchi,whichsubdividewithinthelungstoform lobarandsegmentalbronchiandbronchioles.Platesofcartilagegraduallyreplace theincompleteringsofcartilagefrommainbronchiandfinallydisappearinthe distalbronchioles.Astheamountof cartilagedecreases,theamountofsmooth muscleincreases. • Alveoli-mainsitesforgasexchange. Comprisedofwallsofsimplesquamous epithelium. • Lungs-houserespiratorypassages smallerthanthemainbronchi.Composed primarilyofalveoliandrespiratory passageways.Stromaisfibrouselastic PREVIEW ONLY • connectivetissue,allowinglungstorecoilpassivelyduringexpiration. Pleurae=producelubricatingfluidandcompartmentaliselungs.Comprisedofserous membranes. TheLowerRespiratorySystem: • Conductingairwaysandgasexchangesurfaces • Thereare3lobesintherightlungand2lobesintheleftlung Conductingairways: • Cartilagetopreventairways collapsing • Smoothmusclewhichcannarrow theairways • Respiratoryepithelium(condition andcleantheair) Levelsoftherespiratorytree: • Cartilagebecomeslessprominent asbranchesgetsmaller. • Branchingofthebronchialtree: tracheaàmainbronchiàlobar bronchiàsegmentalbronchi (cartilagepresent)àbronchioles(nocartilage)àterminalbronchioles(smooth musclecells) Respiratoryepithelium: • Cleansandmoistensairbeforeitreachesthe alveoli • Therespiratoryregionislinedwith pseudostratifiedciliatedcolumnarepitheliumwith numerousgobletcells,whichisfrequentlycalledthe respiratoryepithelium Alveoli: • Respiratorybronchiolesàalveolarductsà alveolarsacsàalveoli • Alveoliparticipateingasexchange,andthus respiratorybronchiolesbegintherespiratoryzoneof therespiratorysystem. • Respiratorybronchiolessubdivideinto severalalveolarducts(simplesquamousepithelium). • Aroundthealveolarductsarenumerous alveoliandalveolarsacs.Analveolarsacconsistsoftwoormorealveolithatsharea commonopening. • Wallsofthealveoliconsistof2typesofalveolarepithelialcells:typeIalveolarcells (squamouspulmonaryepithelialthatformtheliningofthealveolarwall)andtypeII alveolarcells. • TypeIalveolarcellsarethemainsitesofgasexchange. • TypeIIalveolarcells(cuboidalepithelial)secretealveolarfluidwhichkeepsthe surfacebetweenthecellsandairmoist.Inthealveolarfluidissurfactant-acomplex PREVIEW ONLY • • mixtureofphospholipidsandlipoproteins.Surfactantlowersthesurfacetensionof alveolarfluid. Alveolarmacrophages(dustcells)arealsoassociatedwiththealveolarwall-these arephagocytesthatremovefinedustparticlesandotherdebrisfromthealveolar spaces. ExchangeofO2andCO2betweentheairspacesinthelungsandthebloodoccurs throughdiffusionacrossthealveolarandcapillarywalls.Thealveolarandcapillary wallsformtherespiratorymembrane. PREVIEW ONLY