Download The Human Respiratory System

TheHumanRespiratorySystem
RosalieCrawford-VeronicaRevel
FondazioneLiceoLinguisticoCourmayeur
Respiration
• Inbiology,respirationhastwomeanings:
-atthecellularlevel,itreferstothe
chemicalreactionsthattakeplaceinthe
mitochondria,whichrequireoxygen,and
aretheprinciplesourceofenergyfor
eukaryoticcells;
-atthelevelofthewholeorganism,itrefers
totheprocessoftakinginoxygenfromthe
environmentandgivingcarbondioxide
backtoit.
• CellsneedoxygentogenerateATPintheir
mitochondria
• Ofallorgans,yourliverhasthegreatestneed:
81litresofoxygenaday,whileyourbrain
requires76litres.
• Atopmarathonerusesabout500litresof
oxygeninthecourseofarace.
• Themainphysiologicaldifferencebetweena
sedentarypersonandarunneristhenumberof
mitochondriapercell,whichincreaseswith
training
Thehumanrespiratorysystem
Apairofhumanlungshassome300millionalveoli,wheregasexchange
takesplace,providingarespiratorysurfaceofabout70squaremetres.
Thehumanrespiratorysystem
Airentersthroughthenoseormouthandpasses
intothepharynx,pastthelarynx,anddownthe
trachea,bronchiandbronchiolestothealveoliin
thelungs.
Gasexchangetakesplaceinthealveoli.The
barrierbetweentheairinanalveolusandthe
bloodinitscapillariesisonly0.5micrometre.
Oxygenandcarbondioxidediffuseintoandoutof
thebloodstreamthroughthecapillaries
surroundingthewallsofthealveoli.
• Thetrachea,bronchiandbronchioles,which
servemainlytotransportairbybulkflow,
arelinedwithepithelialcells.
• Theseincludebothmucus-secretingand
ciliatedcells.
• Themucuscoatstheepitheliumofthe
respiratorysystemandtrapsforeign
particles.
• Theciliabeatcontinuously,pushingmucus
andforeignparticlestowardthepharynx,to
beexpelled.
Mechanicsofrespiration
• Airflowsintooroutofthelungswhenthe
airpressurewithinthealveolidiffersfrom
thepressureoftheexternalair
(atmosphericpressure).
• Thepressureinthelungsisvariedby
changesinthevolumeofthethoraciccavity,
causedbythecontractionandrelaxationof
thediaphragmandofintercostal(“betweenthe-ribs”)muscles.
Transportandexchangeofgases
• Oxygenisalmostinsolubleinbloodplasma.
• Thebloodtransportsoxygenthankstorespiratory
pigmentswhich,invertebrates,arecalled
hemoglobin.Eachhemoglobinmoleculecanbind
fourmoleculesofoxygen.
• Inthecapillariesofthealveoli,wherethepartial
pressureofoxygenishigh,mostofthehemoglobin
iscombinedwithoxygen.
• Inthetissues,wherethepartialpressureislower,
oxygenisreleasedfromthehemoglobinmolecules
intotheplasmaanddiffusesintothetissues.
• Carbondioxideismoresolublethanoxygen
andsomeofitisdissolvedintheblood.
• However,mostCO2reactswithwaterto
formcarbonicacid,aweakacidthat
dissociatestoformbicarbonate(HCO3-)and
hydrogen(H+)ions:
• CO2+H2OH2CO3HCO3+H+
CarbonWater
dioxide
CarbonicBicarbonateHydrogen
acidion ion
• Thereactioncangoineitherdirection,
dependingonthepartialpressureofcarbon
dioxideintheblood.
ControlofRespiration
• Therateanddepthofrespirationarecontrolledby
respiratoryneuronsinthebrainstemwhichactivatemotor
neuronsinthespinalcordthatcausethediaphragmand
intercostalmusclestocontract.
• Inaddition,chemoreceptorcells,locatedinthecarotid
arteries,signaltherespiratoryneuronswhenthe
concentrationofoxygendecreases.
• Centresinthebrainandchemoreceptorssimultaneously
monitortheconcentrationofdissolvedcarbondioxideand
hydrogen.
• Thesystemishighlysensitivetotheslightestchangesin
thechemicalcompositionoftheblood(particularly
hydrogenion,whichreflectstheconcentrationofcarbon
dioxide)
Cancerofthelungsandbronchi
• Italyhasthe4°highestrateofdeathsfromcancer
ofthelungsintheworld.
• Thedelicatetissuesofthealveoliofthelungsare
normallyprotectedfrominfectious
microorganismsandharmfulsubstancesbythe
actionofciliatedepithelialcellsliningthetrachea
andbronchi.Cigarettesmokeparalysesthecilia,
allowingforeigninvaderstoenterthecellsand
initiateseriousdamageanddisease.
Exposuretocigarettesmoke
• Inadditiontoimpairingtherespiratorysystem’s
naturaldefences,cigarettesmokeexposesthe
tissuesofthelungstoatleast43known
carcinogens.
• Long-termexposurecauses:
chronicbronchitis,characterizedbyareductionin
thediameterofpassagewaysandexcessivemucus
production;
emphysema,wherethefragilealveoliwallsbreak
downandarereplacedbyinelasticscartissue
ManversusMountain
Untilrecently,about6,000
metreswasconsideredtobe
thelimitforhumansurvival.
In1978,ReinholdMessner&
PeterHabelerwerethefirst
toclimbMt.Everest8,848
withoutoxygen,raisingnew
questionsabout
physiologicaladaptability.
WHATHAPPENSTOOUR
BREATHINGATTHAT
ALTITUDE??
• Messnerdescribedfeeling
“asthoughIwouldburst
apart”.Hesaidhefeltthat
hismindwasdead.At
8,800m,theycollapsed
every10to15feetandlay
inthesnow.Atthesummit,
hewasquotedassaying,
“Iamnothingmorethana
singlenarrowgasping
lung,floatingoverthe
mistsandsummits."
TheAmericanMedicalResearch
Expedition’sfindings.
• Survivalatextremealtitudesdependson
hyperventilation–extremelydeepbreathing.
• Thepartialpressureofoxygeninthebloodisless
thanonethirdthepartialpressureatsealeveland
workcapacityisseverelydiminished.
• Strikingchangesinmetabolismandbrainfunction.
(extremelossofbodyweight)
• Verballearningandshort-termmemorydeclined.
• http://www.himalayanclub.org/journal/american
-medical-research-expedition-to-everest-1981/
Functionsandcommon,everyday,less
technicalterms
Epiglottis
asmallpieceoffleshatthebackof
yourtonguethatclosesyourtrachea
whenyouswallowfood.
Trachea
windpipe,thetubeatthebackof
yourthroatthatairtravelsdown.
partofyourthroatthatleadsfrom
yourmouthtoyouroesophagus.
Pharynx
Oesophagus
thetubethatcarriesfoodfromyour
mouthtoyourstomach.
Larynx
voicebox,theorganinyour
throatthatcontainsvocalchords,
whichproducesound
Verbsnecessarytoknowtobeable
totalkabouttherespiratorysystem
•
•
•
•
•
•
•
•
•
•
Toflow
Tocoat
Togenerate
Todiffuse
Toprovide
Toline
Topush
Toexpel
Todissolve
Toallow
•
•
•
•
•
•
•
•
•
Tosignal
Toreflect
Toimpair
Tolocate
Torequire
Toparalyse
Totakeplace
Todifferfrom
Tobreakdown
Anomalousplurals
•
•
•
•
•
•
•
•
•
•
pharynx
larynx
bronchus
medium
criterion
(hypo)thesis
crisis
syllabus
datum
phenomenon
•
•
•
•
•
•
•
•
•
•
pharynges
larynges
bronchi
media
criteria
(hypo)theses
crises
syllabi(butalsosyllabuses
data
phenomena
Somebrainteasers
• Ifyouweresufferingfromacold,wouldyoupurchasea
newremedythatpromisestosuppressthesecretionof
mucusintherespiratorytractandrelievethesymptoms?
Why(not)?
• Isitpossibletocommitsuicidebydeliberatelyholding
yourbreath?
• Howwouldyourecognisethesymptomsandwhat
assistancewouldyougivetoavictimofcarbonmonoxide
poisoning?
• Whatwouldyoutellaperson/afamilymemberwho
insistsonsmokingwhileinyourcompany?
• Whatwouldyoudotohelpafriendwhoyoususpectis
sufferingfromalpinesickness?
BBCscience:humanbodyandmind
http://www.bbc.co.uk/science/humanbody/
http://www.bbc.co.u
k/science/humanbo
dy/body/index_inter
activebody.shtml
Play theinteractive
games to revisethe
position oforgans,
musclesandbones.
Aggiungeretitoloparagrafo.Modello
testoaelencopunti.