Phys Exam 3

Question 1

Basic principles of blood flow and pressure

Answer 1

• fluid that flows througha tube requires a pressure gradient
• pressure in the cardiovascular system is produced by the heart
• fluid flow through a tube is influenced by resistance (R). Flow is proportional to 1/R
• R depends on radius. R is proportional to 1/rad^4
• changes in resistance result from vasoconstriction and dilation
• pressure decreases as fluid traels down the tube due to friction

Question 2

elastic arterties serve as a

Answer 2

pressure reservoir

Question 3

each side of the heart functions as

Answer 3

an independent pump

Question 4

arterioles are the site of

Answer 4

variable resistance: chooses where blood goes and regulates pressure by changing resistance

Question 5

capillaries are the site for

Answer 5

exchange

Question 6

systemic veins have

Answer 6

high compliance, not very elastic = volume reservoir

Question 7

allocation of blood flow to body structures is determined by

Answer 7

changes in arteriolar resistance
- arranged in parallel
- controlled individually
- smooth muscle causes vasoconstriction/dilation

Question 8

vasoconstriction at a specific site results in

Answer 8

decrease in pressure downstream, which causes an increase in pressure upstream

Question 9

velocity is inversely proportional

Answer 9

cross sectional area of vessels
- capillaries have largest cross-sectional area, thus having the lowest velocity (allowing for diffusion)

Question 10

three mechanisms of exchange at capillaries

Answer 10

diffusion, vesicular transport, bulk flow
- diffusion for small solutes
- vesicular transport for larger solutes and proteins
- bulk flow for water and solutes

Question 11

bulk flow two possibilites

Answer 11

filtration: fluid going from plasma to the interstitial fluid
absorption: going from interstital fluid back into the plasma

Question 12

bulk flow is determined by

Answer 12

hydrostatic pressure - lower at venous end due to friction
colloid osmotic pressure:
- osmotic pressure resulting from proteins restricted to plasme, not the same as total osmotic pressure
- does not vary across capillary bed

Question 13

if NFP > 0

Answer 13

net filtration, arterial end

Question 14

if NFP < 0

Answer 14

net absorption, venous end

Question 15

filtration at arterial end usually exceeds absorption at venous end, leading to

Answer 15

3L of fluid lost from plasma per day

Question 16

lymphatic system job

Answer 16

• return excess interstitial fluid (lymph) to the blood
• returns any filtered protein to the blood
• filters our pathogens at lymph nodes
• absorbs fats in the small intestine

Question 17

driving pressure of blood pressure

Answer 17

pressure created in ventricles that is transferred to the arteries

Question 18

as blood travels through arteries, capillaries, veins, the pressure

Answer 18

decreases

Question 19

elastic arteries serve as a pressure reservoir by

Answer 19

• stretching during systole
• elastic recoil during diastole: maintains driving pressure
• backward flow during diastole prevented by semilunar valves

Question 20

measures of blood pressure

Answer 20

systolic: ventricular systole
diastolic: ventricular diastole

Question 21

pulse pressure

Answer 21

sBP- dBP

Question 22

mean arterial pressure (MAP)

Answer 22

diastolic pressure + 1/3 pulse pressure
MAP = CO x TPR (total peripheral resistance)

Question 23

the driving pressure for blood flow to tissues and indicative of whether there’s enough pressure to perfuse all organs

Answer 23

mean arterial pressure. Also depends on flow in vs flow out

Question 24

total peripheral resistance (TPR)

Answer 24

resistance to flow out of arteris, due to arterioles

Question 25

factors influencing MAP

Answer 25

• cardiac output
• diameter of arterioles
• blood volume
• diameter of veins

Question 26

cardiac output (CO) and MAP

Answer 26

as CO increases, MAP increases

Question 27

diameter of arterioles and MAP

Answer 27

(TPR) a smaller diameter increases TPR and increases MAP