respiration in humans notes

nostril pharynx larynx/voicebox trachea/windpipe lungs ribs bronchus(plural:bronchi) intercostal bronchiolesmuscles alveoli diaphragm PARTSOFTHERESPIRATORYSYSTEM Inoseandnostrils · airentersthroughthenostrils wallsofnostrilshavenasalhairandmucousmembranesthatproducemucus FUNCTION hairsandmucustrapdust,foreignparticles mucuswarmsandmoistensair sensorycellsinmucousmembranedetectsharmfulchemicals 2trachea airwaythatliesinfrontoftheoesophagus routetakenbyairasweinhale: tracheaissupportedbyC-shapedringsofcartilagetoensurethatthetracheaisalwayskeptopen throughnostrils ↓ pharynxlumen ↓C-shapedcartilage larynxlarynx ↓ trachea _trachea bronchusbronchus ↓bronchidlesbronchidles rightmain leftmain ↓bronchus bronchus alveolialveoli

3bronchidbronchicles thetracheabranchesintotwotubescalledthebronchi · eachbronchusbranchesrepeatedlyandendsin numerousbronchioles eachbronchioleendsinaclusterofairsacscalledalveoli wheregaseousexchangetakesplace 4epitheliumoftracheaandbronchi · themembraneintheinnerwallofthelumenofthe tracheaandbronchiiscalledtheepithelium consistsof2typesofcells1.glandcellssecretemucusthattrapsdustparticlesbacteriaintheairpassage2.ciliatedcellshavecilia,whichsweepthemucuscontainingdustparticlesin bronchiandtracheaintothepharnyx canbecoughedoutthroughthepharnyx orbeswallowedintotheoesophagus 5alveoli· thesitesofgasexchange· numerousalveoliarefoundinthelungs· eachalveclusissurroundedbyanetwork ofbloodcapillaries

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HOWISOXYGENABSORBEDFROMTHELUNGSINTOBLOODANDINTOCELLSOFTISSUES? 1.alveolaraircontainsahigherconcentrationofoxygenthanthebloodplasma 2.oxygendissolvesinthethinfilmofmoistureintheinnerwallofthealveolus andthendiffuseintobloodcapillaries33oxygencombinesreversiblywithhaemoglobininredbloodcellstoformexyhaemoglobin4.Whenbloodpassesthroughoxygen-poortissues,theexyhaemoglobinreleasesoxygen5.whichwilldiffusethroughthewallsofthebloodcapillariesintothecellsofthetissues BREATHING· partofthegasexchangeprocess · referstothemuscularcontractionsandmovementoftheribswhichresultinair movinginandoutofthelungs· breathingmovementsconsistofCphases: Itakinginofaircalledinhalationorinspiration 2.givingoutofaircalledexhalationorexpiration STRUCTURESWITHINTHETHORACICCAVITY · thethoraciccavityisthespaceinthebodythatisprotectedbytheribcage,aswellastheassociatedskinandmuscles Isetsofintercostalmusclescanbefoundbetweentheribs· theintercostalmusclesandthediaphragmattheribcageenablethechangein volumeofthethoraciccavity 6intercostalmuscles · externalintercostalmusclesandinternalintercostalmuscles arefoundbetweentheribs ⊥theyareantagonisticmuscles

7diaphragm· foundbelowthorax madeupofadome-shapedsheetofdiaphragmmuscles · whendiaphragmmusclescontract,diaphragmflattensdownwards·whendiaphragmmusclesrelax,diaphragmarchesupwardsandbecomesdome-shaped BREATHINGININSPIRATION · diaphragmmusclescontract,diaphragmflattensdownwards· externalintercostalmusclescontract,internalintercostalmusclesrelax· ribsswingupwardsandinwards volumeofthoraciccavityincreases ⊥decreasesairpressureinthelungs ⊥atmosphericpressureisnowhigherthanthepressurewithinthelungs ⊥causesairfromtheatmospheretobeforcedintothelungs BREATHINGOUTEXPIRATION · diaphragmmusclesrelax,diaphragmarchesupwardsandbecomesdome-shaped · externalintercostalmusclesrelax,internalintercostalmusclescontract ribsswingdownwardsandinwards· volumeofthoraciccavitydecreases ⊥increasesairpressureinthelungs⊥atmosphericpressureisnowlowerthanthepressurewithinthelungs⊥thiscausestheairinlungstobeforcedoutofthelungs

SMOKINGEEFFECTSOFTOBACCOSMOKE majortoxiccomponentsoftobaccosmoke · nicotineisanaddictivedrug,thatcauses addictiontosmoking nicotineincreasesthechancesofbloodclotin nicotinebloodvessels,increasingtheriskof coronaryheartdisease · nicotinecausesthereleaseofthehormone, adrenaline,whichincreasesheartrateand bloodpressure · carbonmonoxidebindsirreversiblywith haemoglobininredbloodcellstoform carboxyhaemoglobin carbon ⊥reducestheabilityofhaemoglobintobindmonoxidetooxygenandreducestheefficiencyof oxygentransport carbonmonoxidealsoincreasestherisk ofcoronaryheartdisease · tarparalysesciliainairpassages mucuscannotbesweptupinairpassage,soparticlesinmucuscannotberemoved tar ⊥thiscanleadtoviolentandpersistent coughing(chronicbronchitis tarcontainscancer-causingchemicals thatcauseuncontrolledcelldivisioninthe lungs,increasingtheriskoflungcancer irritant · paralysecilialiningintheairpassages particles· increaseriskofchronicbronchitisand emphysema

DISEASESASSOCIATEDWITHSMOKING 1.chronicbronchitis prolongedexposuretoirritantparticlesintobaccosmokeleadsto: · epitheliumliningofairpassagesbecomeinflammed,excessive mucussecretedbyepithelium· ciliaontheepitheliumparalysed⊥mucusanddustparticlescannotberemoved· airpassagebecomesblockedandbreathingbecomesdifficult persistentandviolentcoughingtoclearairpassages 2.emphysema long-termpersistentandviolentcoughingmayleadtoemphysema partitionwallsbetweenalveolibreakdownbecauseoftheforce fromthecoughing thisresultsindecreasedsurfaceareaforgaseousexchange thelungslosetheirelasticityandbecomeinflatedwithair· breathingbecomesdifficult,leadingtowheezingandseverebreathlessness 33lungcancer · carcinogens(substancesthatcancausecancer)intobaccosmoke cancausemutationsintheDNAinlungcells thiscauseslungcancer,whichisaresultofuncontrolleddivision ofcellsinthelungs,producinglumpsoftissues(tumors)inlungs

RESPIRATION theoxidationoffoodsubstanceswiththereleaseofenergy inlivingcells 2typesofrespiration 1)aerobicrespiration(requiresoxygen 2)anaerobicrespiration(doesnotrequireoxygen) bothtypesutiliseglucoseasarespiratorysubstrate · respirationusbreathing 1)respirationandbreathingaredifferentbutrelatedprocesses 2)respiration:oxidationoffoodmoleculeswithinlivingcells toreleaseenergy 3)breathing:exchangeofgasesbetweenthebodyand thesurroundings4)oxygenrequiredforaerobicrespirationistakeninwhen webreathein;carbondioxideproducedisgivenout whenwebreatheout AEROBICRESPIRATION ⊥breakdownoffoodsubstancesinthepresenceofoxygenwith thereleaseofalargeamountofenergy· occursintheMitochondria· duringrespiration,glucoseisoxidised, producingcarbon dioxideandwater,andreleasingalargeamount ofenergy Iglucose+oxygen,carbondioxide+water

ANAEROBICRESPIRATION ⊥breakdownoffoodsubstancesintheabsenceofoxygen anaerobicanaerobicrespirationrespiration Ta ke splacein slessefficient thecytoplasm hanaerobicofthecellrespiration; lessenergyisreleasedduringanaerobicrespiration inhumans,anaerobicrespirationcanhappeninmusclecells duringvigorousexercise · inmusclecells,thisprocessproduceslacticacidand releasesasmallamountofenergy glucose, lacticacid AEROBICANAEROBICRESPIRATIONINHUMANS· therearemorevigorousmuscularcontractionsduringexerciseƑ · moreenergyisrequiredformorevigorousmuscularcontractions · so,ahigherrateofaerobicrespirationtakesplaceinmusclecells 1)glucoseisoxidisedatahigherratetoreleaseenergyata higherrate· breathingrateincreases: 1)oxygenistakeninatahigherrate,sothataerobic respirationcantakeplaceatahigherrate,for moreefficienreleaseofenergy - duringexercise 2)carbondioxideisalsoremovedfromthebodyata higherrate · heartrateincreases: 1)sooxygenandglucosecanbepumpedtothe musclesatahigherrate 2)thisallowshigherrateofaerobicrespirationin musclecells,toreleaseenergyfaster _

AEROBICANAEROBICRESPIRATIONINHUMANS · duringintenseorlongperiodsofvigorousexercise,oxygensupplied_ tomusclesisnotenoughtomeettheoxygendemand amountofoxygentakeninisle