BloodPressure-InterlakeSchoolDivision血压茵特拉根学校分部

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1、BloodPressureIfbloodistoreachthehandsandfeet,thebrain,andeveryotherpartofthebody,itmustbepumpedoutoftheheartunderconsiderablepressure.Bloodpressure–theforceofbloodagainstthewallsofarteries.Toreachallpartsofthebody,theheartpumpsbloodathighpressure.Thehighestpressure

2、occursintheaorta.Asbloodpassesintosmallervesselsandthedistancefromtheheartincreases,thepressurereduces.Thepressureinanyarteryvariesasaresultoffivemajorfactors:Thevolume(amount)ofblood.Ifaninjuredpersonhaslostalotofblood,thepressuredropsbecauseofthedecreaseinvolumeo

3、fblood.Theheartrate.Morepressurebuildsupastheheartpumpsmorebloodout.Pressurefallsasheartratedecreases(especiallyduringrest/sleep).Thesizeofthearteries.Whenarteriesdilate,thevolumeofthevesselsincreasesandthepressurefalls.Ifthearteriesconstrict,pressureisbuiltupbecau

4、seoftheextraresistancetobloodflow.Theelasticity.Flexibleandelasticarteriesexpandasasurgeofbloodisforcedfromtheheart(andrelaxaftersurgepasses).Iftheycannotstretchthisway,theyarehardened.Theviscosityoftheblood.Thicknessofblood.Thick,stickyfluidsflowlessreadilythanthi

5、n,wateryfluids.MeasuringBloodPressureTwodifferentpressuresaremeasuredinabloodpressurereading:Systolicpressure–amountofpressurethatthebloodexertsonthewallsofthearterieswhentheventriclescontract.Diastolicpressureistheamountofpressurethatthebloodexertsonthearterywalls

6、whentheventriclesarerelaxed.Bloodpressurecanbemeasuredusingasphygmomanometer.Aninflatablerubbercuffiswrappedaroundtheupperarm.Airispumpedintothecuff.Cuffpressesonarteriesinthearm,untilthebloodflowthroughthearteriesstops.Astethoscopeisplacedoveroneofthearteriesinthe

7、elbow:Airisgraduallyreleased.Atfirstnosound,butthenasharptappingsoundisheard:Madebythebloodspurtingthroughanarrowopeninginthecompressedartery.Thereadingjustasthissoundisheardisthesystolicpressure.Asmoreairisreleasedfromthecuff,thesoundismuffledandstops.Thepressurer

8、eadingjustassoundstopsisthediastolicpressure.Bloodpressureismeasuredinmillimetersofmercury(mmHg).expressedasaratioofsystolicpressure:diastolicpre