Respiratory SystemWord文档下载推荐.docx

Respiratory SystemWord文档下载推荐.docx

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1.Describethestructureandfunctionofthehumanheart.

A.TheHeart

1.Thecentralorganofthecardiovascularsystemistheheart,themuscularorganthatpumpsbloodthroughanintricatenetworkofbloodvessels

a.Theheartlieswithinthethoracic（chest）cavity,behindthesternum（breastbone）andbetweenthetwolungs

b.Atough,saclikemembranecalledthepericardiumsurroundstheheartandsecretesafluidthatreducesfrictionastheheartbeats

2.Aseptumverticallydividestheheartintotwosides

a.Therightsidepumpsbloodtothelungs,andtheleftsidepumpsbloodtotheotherpartsofthebody

b.Eachsideoftheheartisdividedintoanupperandlowerchamber

c.Eachupperchamberiscalledanatrium,andeachlowerchamberiscalledaventricle

3.Aone-wayvalveseparateseachatriumfromtheventriclebeneathit

a.Thesevalvesarecalledatrioventricular（AV）valves

b.Theyconsistofflapsoftissuethatopeninonlyonedirection

c.TheAVvalveontherightsideiscalledthetricuspidvalve

d.Themitralvalve,alsocalledthebicuspidvalve,isontheleft

e.Astheventriclespump,bloodpressureclosestheAVvalves,preventingbloodfromflowingbackwardfromtheventriclestotheatria

4.Fromtheventricles,bloodflowsoutoftheheartintolargevessels

a.Asemilunar（SL）valveseparatestheventriclesfromtheselargevesselsoneachsideoftheheart

b.TheSLvalveontherightsideisknownasthepulmonaryvalve,andtheSLvalveontheleftsideisknownastheaorticvalve

c.TheSLvalvespreventbloodfromflowingbackintotheventricleswhentheheartrelaxes

B.ControloftheHeartbeat

1.Donebythesinoatrial（SA）node（akathepacemaker）

a.TheelectricalimpulsesoftheSAnodereachtheAVnode,whichinturncausestheventriclestocontract,slightlyaftertheatria

2.Theheartbeathas2phases:

systoleanddiastole

a.Phaseone,systole,occurswhentheventriclescontract,whichclosestheAVvalvesandopenstheSLvalves

b.Phasetwo,diastole,occurswhentheventriclesrelax,closingtheSLvalvesandopeningtheAVvalves

1）Ifonevalvefailstocloseproperly,youdevelopwhatisknownasaheartmurmur

2.Tracetheflowofbloodthroughtheheartandbody.

A.Therightatriumtherightventriclethepulmonaryarterieslungstheleftatriumtheleftventricletheaortathebodythevenacava

B.CirculationintheHeart

1.Bloodreturningtotheheartfrompartsofthebodyotherthanthelungshasahighconcentrationofcarbondioxideandalowconcentrationofoxygen

a.Thisdeoxygenatedbloodenterstherightatrium

b.Therightatriumpumpsthedeoxygenatedbloodintotherightventricle

c.Themusclesoftherightventriclecontractandforcethebloodintothepulmonaryarteries,whichleadtothelungs

d.Inthelungs,thecarbondioxidediffusesoutofthebloodandoxygendiffusesintotheblood

e.Theoxygenatedbloodreturnstotheleftatriumoftheheart

f.Theoxygenatedbloodisthenpumpedintotheleftventricle

g.Contractionofthemuscularwallsoftheleftventricleforcethebloodintoalargebloodvesselcalledtheaorta

h.Fromtheaorta,bloodistransportedtoallpartsofthebodyexceptthelungs

i.Theleftventricleisthethickestchamberoftheheartbecauseithastodothemostworktopumpbloodtoallpartsofthebody

3.Distinguishbetweenarteries,veins,andcapillariesintermsoftheirstructureandfunction.

C.BloodVessels

1.Thecirculatorysystemisknownasaclosedsystembecausethebloodiscontainedwithineithertheheartorthebloodvesselsatalltimes

a.Thistypeofsystemdiffersfromanopensystem,inwhichbloodleavesthevesselsandcirculateswithintissuesthroughouttheorganism’sbody

b.Thebloodvesselsthatarepartoftheclosedcirculatorysystemofhumansformavastnetworktohelpkeepthebloodflowinginonedirection

2.Arteries

a.Thelarge,muscularvesselsthatcarrybloodawayfromtheheartarecalledarteries

1）Thethickwallsofthearterieshavethreelayers:

aninnerendotheliallayer,amiddlelayerofsmoothmuscle,andanouterlayerofconnectivetissue

2）Thisstructuregivesarteriesacombinationofstrengthandelasticity,whichallowsthemtostretchaspressurizedbloodentersfromtheheart

3）Thestretchingofyourarteriesisknownasyourp