topic 6: human physiology
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Topic6:HumanPhysiology6.2TheBloodSystem
D.4TheHeart
EssentialQuestions:6.2Thebloodsystemcontinuouslytransportssubstancesto
cellsandsimultaneouslycollectswasteproducts.D.3Thechemicalcompositionofbloodisregulatedbytheliver.D.4Internalandexternalfactorsinfluencetheheartfunction.
OurCirculatorySystem
• Systemcomprisedofaheart,bloodvessels,&lymphglands
• Worktogethertosupplythebodytissueswithnourishmentandcollectwastematerials.
Arteries,Veins,Capillaries
CrossSectionofanArteryandaVein
OrganizationofArteries,Arterioles,Capillaries,VenulesandVeins
Arteries• Haveathickouterlayer
oflongitudinalcollagenandelastinfibers
• Toavoidleaksandbulges
• Thickwalled• Towithstandhighpressure
• NarrowLumen• Maintainshighpressureinsidearteries
• Circularelasticfibresandmusclefibres
(elastic-liketissues)• Towithstandthepressurefromtheheart’sbeating• Tohelppumpbloodaftereachcontractionofheart
• Porous• Allowsplasmatoleakoutandformtissuefluid• Phagocytescanalsopassthroughpores
• Smalldiameter(narrowlumen)• Bloodcellspassthroughinsinglefile• Allowsformanycapillariestofitintoasmallspace
• Semi-permeablemembrane• allowsnutrients,oxygen,andwatertodiffusefrombloodintothetissues
Capillaries
• Connectarteriestoveins
• Wallisonecellthick• Thusshortdistancefordiffusiontooccur
• Thin-walled
Veins• Thinouterlayeroflongitudinalcollagenandelastinfibres
• Becausepressureislow
• Thin,collapsiblewalls• Fewcircularelasticfibresandmusclefibresasblooddoesnotflowinpulses• Nearbymusclescanhelppushbloodbacktowardheart
• WideLumen• Accommodatetheslowflowingblood
• Valves• Preventbloodfromreversingflow
CrossSectionofBloodVessels
HistologyofArteries&Veins
Source:legacy.owensboro.kctcs.edu
ComparisonofArteries,VeinsandCapillaries
FromPearsonHLBiology
Atherosclerosis
• Developedbydepositsofplaque(cholesterol,lipids,calcium,celldebris)accumulateatatearintheinnerlayeroftheartery
• Hardens,andoccludesthelumen
• Bloodflowtotissuesdecreasesandaclotcanbecomelodgedandcompletelyobstructcirculation
• Canleadtoheartattack
TheHeart
TheHeart-Valves
Differentnamesforthevalvesoftheheart:
FromPearsonHLBiology
MyogenicControloftheHeart
• Heartismadeupofcardiacmuscle– CardiacmuscleisMYOGENIC-meaningitnaturallycontractsandrelaxes(originatesfromtheheartitself)• Itreceivesnocontrolfromanervetomakeitcontract• ItsAUTOMATIC!
• Somecontrolbyautonomicnervoussystem• RespondstochangesinbodyAUTOMATICALLY• Example:increasedbodyactivity=running
• Electricalimpulsescausesregularcontractionsoftheatriafirst,thentheventricles=heartbeat
BloodComposition
• Transport(Highway)aroundbody• nutrients,• Gases(eg.oxygenandcarbondioxide)• Hormones(Communication,Homeostasis)• Antibodies,leucocytes(WBC)• urea• Heat
BloodComposition
• Plasma• Fluid• carriesallothercomponentsofblood,nutrientsandwastes
• Erythrocytes(RBC’s)• Producedinbonemarrow (oflargebones)• Transportsoxygenandcarbondioxide
BloodComposition• LymphocytesandPhagocytes(WBC’s)
• Producedinbonemarrow• Belongstoimmunesystem
• Platelets• Cellfragmentsthataidinbloodclotting
Adropofbloodcontainsapproximately:- 5millionRBC- 10,000WBC- 250,000platelets
Topic6:HumanPhysiology6.2TheBloodSystem
D.4TheHeart
EssentialQuestions:6.2Thebloodsystemcontinuouslytransportssubstancesto
cellsandsimultaneouslycollectswasteproducts..
D.4Internalandexternalfactorsinfluencetheheartfunction.
OurCirculatorysystemisadoublecirculatorysystem.Ithastwoparts:
the left side of the system
deals with oxygenated
blood.
the right side of the system
deals with deoxygenated
blood.
Lungs
Bodycells
TypesofCirculation
1) Pulmonary- movementofbloodàheart-lungs–heart
2) Systemic- Movementofbloodàheart–body–heart
3) Coronary -bloodvesselsthatsupplythemuscleoftheheartwith oxygen/nutrientsandremovewasteproducts
Red portion of heart and red blood vessels carry oxygen-rich blood.
Blue portion of heart and blue blood vessels carry oxygen-poor blood.
PulmonaryCirculation
CardiacCycle- Seriesofeventsreferredtoasoneheartbeat- Frequencyofthecardiaccycleisyourheartrate(measuredinbeatsperminute)
- 80beatsmin-1=80cardiaccycleseveryminute
Systole(sis-tol-ee)Diastole(di-as-tol-ee)
Contractionoftheheart RelaxationoftheheartNote:Bothatriacontractatthesametime,andboth
ventriclescontractatthesametime,justamomentlaterthen
theatria
Diastole(=60-80mmHgadults)• Both Chambers are at rest (no
contracting)
• Minimum pressure in the arteries
• Atrial pressure is slightly higher then ventricular pressure keeping the left atrioventricular valve open
• Blood moves passively from atrium into ventricle
• The valve of the aorta is kept closed = no backflow
Systole(=90-120mmHgadults)• Contraction
• Maximum pressure on the arteries
• Atria in Systole first –generates a little pressure to move any remaining blood into the ventricle
• Ventricles in systole – pressure inside is greater then the atrium so the valves close to prevent backflow (=lub)
• Ventricular pressure builds up until pressure becomes greater in the ventricle then the aorta causing the semilunar valve to open. Blood is forced into aorta
• Ventricle finishes contraction and semilunar valve closes (=dub)
BloodPressure• Anadultisconsideredsufferingfromhypotensionifthediastolicreadingis<60mmHgandsystolicreadingis<90mmHg
• Prehypertensionifthediastolicreadingis81–89mmHgandsystolicreadingis121–139mmHg
• Stage1Hypertensionifthediastolicreadingis90–99mmHgandsystolicreadingis140–159mmHg
• Stage2Hypertensionifthediastolicreadingis100mmHgandsystolicreadingis160mmHg
OcclusioninCoronaryArtery
• Blockageofoneofthethreemajorcoronaryarteriesortheirbranches
• Heart(oraportionofit)becomesdeprivedofoxygen=myocardialinfarction
http://nursingcrib.com/peir.path.uab.edu
CoronaryCirculation
FromA.D.A.M
• Vesselsdeliveroxygenrichbloodtotheheart
• Highlyaffectedbyatherosclerosiswhichcancauseanginaorheartattack
• CardiaccycleinitiatedbysmallpatchofmusclecalledtheSANode(sino-atrialnode)orPACEMAKER
• Thisnodesetstherhythmforallcardiacmuscle(notthebrain)• Foraheartrateat72beats/min,theSANgeneratesanactionpotentialevery0.8seconds(ataregularfrequency)– Thepacemakercellshaveabuilt-inrhythmthatisfasterthanallotherheartcells
MyogenicControloftheHeart
• SAnodesendsoutanactionpotential(AP)andspreadsoutthroughtheatrialeadingtosystole(contraction)
• SAnode’sAPreachestheatrioventricularnode(AVnode)locatedinthelowerwallofrightatrium/septum
• AVnodesendsoutanewAPthatspreadstobothventriclesaftera0.1seconddelay
• PurkinjefibreshelpspreadtheAPthroughthethickwallsoftheventriclescausingventricularsystole
MyogenicControloftheHeart
Electrocardiograms(ECG’s)
• Usedtomeasureheartrate
• Eacheventinthecardiaccyclehasadistinctivewaveform
• Everyrepeatingpatternisarepresentationofonecardiaccycle
HowtoReadanECG
• Pwave– showsvoltageofAPfromSA
node=atrialsystole
• Qpoint– AVnodesendsitsimpulse
• QRScomplex– APfromtheAVnodespreads
downPurkinjefibreswithinventricles(=ventricularsystole)
• Twave– repolarizationofAVnode
(anotherheartbeatcannotoccuruntilrepolarizationiscomplete)
Electrocardiograms(ECG’s)
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