lecture16-11

lecture16-11 - Lecture15- Lecture16-the circulatory system...

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Parts of the Circulation arteries— Transport blood at high pressure to the tissues,rapid blood flow. Havethick, strong vascular walls. Serve as pressure reservoirs. Have elastic walls (can stretch and re-form), due to high amount of protein elastin inwalls. arterioles Control blood flow into capillaries. Capable of narrowing (constricting) widening (dilating) to direct blood to where it is needed. capillaries site of exchange offluid, nutrients, salts,hormones, O 2 , ect. v enules Collect bloodfrom capillaries v eins Take blood back to heart. Serve as reservoirs of blood. Lowpressure have thinmuscular walls. Bycontracting they canforce moreblood backinto the circulation. They contain the greatest amount of blood. systemiccirculation - 84% of blood volume •the entire system is lined by endothelial cells . These are the cells that contact the blood Lecture 16- the circulatory system - - - -
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Arteries: 1/3 of blood in arteries is injected into the arterioles with each ventricular contraction. The rest of the blood is held in the elastic artery as it swells (distends). During ventricular relaxation the artery walls recoil and propel the rest of the blood into the arterioles. This keeps the arterioles continuously pressurized. 1/3 systole diastole diastole arterial pressure time systolic pressure 120 mm Hg diastolic pressure 80 mm Hg mean arterial pressure (MAP) [ diastolic pressure + 1/3 (systolic-diastolic)] •the heart is relaxed (diastolic) more than it is contracting (systolic). Thus the mean arterial pressure (MAP) is lower than the average of the two peaks [MAP diastolic pressure + 1/3 (systolic-diastolic)] pulse pressure = systolic – diastolic pressures diastolic systolic MAP pressure 20 40 60 80 AGE •systolic pressure rises much faster with age then does diastolic – a result of atherosclerosis
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•pressure thoughout the circulatory system falls as you move away from the heart, and differences in pressure due to cardiac systole and diastole get muffled.
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This note was uploaded on 02/14/2011 for the course MCDB 111 taught by Professor Smith during the Spring '11 term at UCSB.

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lecture16-11 - Lecture15- Lecture16-the circulatory system...

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