Download LECTURE 7: • Know all the components of the respiratory system

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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
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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
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mixtureofphospholipidsandlipoproteins.Surfactantlowersthesurfacetensionof
alveolarfluid.
Alveolarmacrophages(dustcells)arealsoassociatedwiththealveolarwall-these
arephagocytesthatremovefinedustparticlesandotherdebrisfromthealveolar
spaces.
ExchangeofO2andCO2betweentheairspacesinthelungsandthebloodoccurs
throughdiffusionacrossthealveolarandcapillarywalls.Thealveolarandcapillary
wallsformtherespiratorymembrane.
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