M9: Blood Vessel Physiology

Question 1

hemodynamics

Answer 1

factors affecting blood flow

Question 2

blood flow

Answer 2

volume of blood flow that flows through a tissue in a given time period (e.g. mL/min)

Question 3

total blood flow =

Answer 3

cardiac output

Question 4

mean arterial pressure (MAP)

Answer 4

1/3 (SBP–DBP) +DBP
- “driving pressure” through cardiovascular system
- because more time spent in diastole, MAP will be closer to DBP

Question 5

at which artery is blood pressure normally measured and why?

Answer 5

brachial artery in the arm

Question 6

what blood vessel reduces pulsatile flow and why is this necessary?

Answer 6

arterioles
- too much changing pressures in capillaries would cause them to burst

Question 7

equations for cardiac output

Answer 7

CO = HR x SV
CO = MAP / Resistance

Question 8

process of taking blood pressure

Answer 8

• pressure cuff placed over arm. pressure in cuff is higher than pressure in brachial artery, causes occlusion
• pressure gradually released in cuff
• first KOROTKOFF SOUNDS = point of SPB
• last KOROTKOFF SOUNDS = point of DBP

sounds happen because of turbulent flow in occluded artery, stop because laminar flow returns

Question 9

what factor has the largest impact on blood flow resistance and why?

Answer 9

VESSEL DIAMETER
- because resustance = 1/(diameter of vessel)^4
- small changes in vessel diameter magnify

Question 10

what factors affect blood flow resistance? equations

Answer 10

R ∝ viscosity of blood * length of vessel
R ∝ 1/(diameter of vessel)^4

Question 11

Relationship between velocity of blood flow and x-sectional area?

Answer 11

blood flow inversely related to cross-sectional area of blood vessels
- speed decreases as blood moves into capillaries. WHY?
- pressure drops so velocity drops
- low velocity for gas exchange

Question 12

where does the greatest drop in blood pressure occur?

Answer 12

In the arterioles