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Vascular Function

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imissyou419's version from 2017-01-31 05:03

Section

Question Answer
Consecutive branches of aterial system becomessmaller and smaller, proliferation of more and more blood vessels leading to ↑ TOTAL cross sectional area
Which has larger lumen diameter, vena cava or aorta?vena cava
How much blood flow (L/min) pass through each level (aorta, arterioles, capillaries, venule, veins)?5L/min
Blood velocity (cm/sec) trenddecreasing as you go from aorta -> capillaries then increases again as you go from capillaries -> vena cava
Blood velocity is lowest whengreatest SA, shortest diffusion distance (capillaries)
The greater the resistancethe greater the drop in pressure
Aorta and large arteries resistancevery little resistance to blood flow due to compliance so pressure remains high
Small arteries resistancefall in pressure begins, ↑ resistance begins
Arterioles resistancegreatest resistance (accounting for 1/2 resistance in entire systemic circulation) [b/c small diameter + not compliant (thick walls contain smooth muscle)]
Capillaries resistance↓ p to about ~20 mmHg (from 40 mmHg)
Venous circulation resistancesmall but significant amount of resistance, by the time the blood reaches right atrium, P = 0 mmHg
TPR istotal resistance throughout entire systemic circulation, most TPR in arterioles, little in aorta & arteries & capillaries, least in veins
What is the pressure-resistance throughout pulmonary circulation and why?low pressure-low resistance because heart less muscle on right ventricular wall b/c less distance it travels so don't need to generate as much force so low pressure
Pulse pressure = systolic pressure - diastolic pressure
Pulse pressure is influenced by what1. SV (↑ SV, ↑ P rise and fall during systolic and diastole so ↑ pulse pressure),
2. Compliance of blood vessels in the arterial system (↑ compliance, ↓P rise and fall when SV of blood pumped into arteries "aorta dampens pressure output of left ventricle"
MAP = CO x TPR, 1/3 systole - 2/3 diastole, average pressure throughout entire CARDIAC CYCLE
RPP (rate pressure product) = systolic pressure x HR, measures workload on heart
Flow of a blood vessel depends on1. pressure gradient, 2. resistance (resistance more since r^4)
Q = (P1-P2)R
R = 8Ln/Pir^4
What are the assumptions for Q?1. the tube must be straight, rigid, cylindrical, unbranched, have constant radius.
2. flow is not pulsatie but steady
Arterioles and vein walls outer layerfibrous connective tissue
Arteriole and vein wall middle layersmooth muscle and elastic tissue
Arteriole and vein wall inner layer (tunica interna)endothelial cells
veins have what?valves
capillaries are _layer of endothelial cells1
Aorta has (what kind of walls, with high what tissue)?thin wall, high elastic tissue so can expand to accomodate ejection of blood "shock absorbers" giving pulsatile nature
Arteriole has (what kind of walls, high in what tissue)?thick wall, high smooth muscle (under ANS control) so can adjust diameter to adjust blood flow to tissues, arterioles have highest resistance to blood flow = greatest drop in blood pressure
Capillary hassmall, 1 cell thick so blood flow is lowest, total cross-sectional area highest
Vein hasthin wall, large diameter, smooth muscle so low BP since resistance is low b/c of large vessel radius
Artery hashigh smooth muscle
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