properties of the vascular system

Question 1

two main functions of capillaries

Answer 1

solute exchange and fluid exchange

Question 2

mechanism by which solutes are exchanged

Answer 2

diffusion due to concentration gradients across wall

Question 3

diffusion obeys which law

Answer 3

Fick’s law

Question 4

mechanism by which fluid is exchanged

Answer 4

bulk flow due to pressure gradients across the wall

Question 5

bulk flow obeys which law

Answer 5

starling’s principle

Question 6

explain starling’s principle

Answer 6

flow is affected by plasma protein osmotic pressure as well as hydraulic pressure

Question 7

why does starling’s law apply to capillaries ?

Answer 7

they are permeable to water and small solutes

relatively impermeable to plasma proteins

Question 8

what are the four starling forces?

Answer 8

hydrostatic pressure in capillary and interstitial

oncotic pressure in capillary and interstitial

Question 9

flow at rest

Answer 9

5000ml/min

Question 10

distribution of cardiac output at rest

Answer 10

brain- 650ml, 13%

heart- 215ml, 4%

skeletal muscle- 1030, 20%

skin- 430ml, 9%

kidneys- 950ml- 20%

abdominal organs- 1200ml, 24%

other- 525ml, 10%

Question 11

cardiac output distribution exercise

Answer 11

brain- 750ml, 4%

heart- 750ml, 4%

muscle- 12,500ml 73%

skin- 1900, 11%

kidneys- 600ml, 3%

abdominal organs- 600, 3%

other- 400ml, 2%

Question 12

cardiac output during exercise

Answer 12

17,500 ml/min

Question 13

blood flow definition

Answer 13

refers to the movement of blood through vessels

Question 14

pressure definition

Answer 14

a measure of the force that the blood exerts against the vessel walls

Question 15

which direction does blood flow in?

Answer 15

Along a decreasing pressure gradient, from arteries to capillaries to veins

Question 16

link between velocity of blood flow and cross sectional area

Answer 16

velocity of blood flow varies inversely with the total cross sectional area of blood vessels

as the total cross sectional area of vessels increases, the velocity of flow decreases

Question 17

where is blood flow slowest? + benefit

Answer 17

slowest in capillaries, allows time for exchange

Question 18

resistance definition

Answer 18

force that opposes the flow of a fluid

Question 19

in blood vessels, what causes most of the resistance?

Answer 19

vessel diamater

Question 20

link between blood flow, diameter and resistance

Answer 20

as the diameter decreases, the resistance increases and the blood flow decreases

Question 21

difference between flow rate and velocity

Answer 21

velocity is the speed

flow rate is the volume of fluid passing through an area

Question 22

how else can flow rate be increased?

Answer 22

increasing the diameter

Question 23

viscosity definition

Answer 23

the thickness of fluids that affects their ability to flow

Question 24

viscosity relationship with resistance and flow

Answer 24

directly proportional to resistance

inversely proportional to flow

the thicker the blood, the slower the flow, the greater the resistance

Question 25

anomalous viscosity of blood explained

Answer 25

red blood cells can deform and aggregate, thus viscosity of blood can vary with sheer rate

blood becomes less viscous at high rates, as the blood cells aggregate