hemodynamics

Question 1

pressure

Answer 1

1. highest in aorta
2. Pressure decreases through system, especially in resistance vessels (sm arteries & arterioles)
3. low in capillaries and venous system

Question 2

volume

Answer 2

1. Total blood volume ~ 5 L

2. Largest volume in veins (“capacitance vessels”)

Question 3

flow equation

Answer 3

Q= ΔP/ R

Q: blood flow
P: pressure
R: resistance

Question 4

flow in must equal

Answer 4

flow out

the total flow is constant throughout the CV system

Question 5

Flow (Q)

Answer 5

volume per unit time (ml/min)

CONSTANT through system (since closed loop)

Question 6

cardiac output (CO) =

Answer 6

(Pa - Pv) / TPR

Pa= mean arterial blood pressure
Pv= venous blood pressure
TPR = total peripheral resitance

Question 7

V (Velocity) =

Answer 7

Q/A

Question 8

velocity is highest in the

Answer 8

aorta (lowest total cross sectional area

Question 9

velocity is lowest in the

Answer 9

capillaries (greatest cross sectional area)

Question 10

what is the cardiac output?

Answer 10

the volume of blood pumped per minute by the heart

5L/min at rest

Question 11

Cardiac output corresponds to the

Answer 11

total flow in the cardiovascular system

Question 12

poiseuelle’s Equation

Answer 12

Q = ΔP x (π r^4)/8nl

R is the radius
n is the viscosity
l is the length

Question 13

if you increase radius?

Answer 13

decrease R and increase Q

Question 14

if you increase viscosity?

Answer 14

increase R and thus decrease Q

Question 15

if you increase length?

Answer 15

increase R and thus decrease Q

Question 16

what is the biggest determinant of flow?

Answer 16

Radius because flow is proprotional to the 4th power of the radius

Question 17

Resistance in parallel

Answer 17

decreases the total resistance

Question 18

Rf of a parallel network is ____ than the resistance of a single vessel

Answer 18

lower

Question 19

changing the R of a single vessel effect the system how?

Answer 19

little effect on the whole system

Question 20

the total resistance in the capillary beds is

Answer 20

low and independent of the individual capillaries because there are many parallel vessels.

Question 21

resistance in a series is

Answer 21

additive

Rf= R1 + R2 + R3 + …

Question 22

total resistance of a series is ___ than the resistance of any individual vessel

Answer 22

higher

Question 23

blood flow through a series is

Answer 23

constant, but the pressure drops

Question 24

laminar flow

Answer 24

1. most efficient
2. velocity fastest in the center, zero at the edge
3. flow equation assumes laminar flow. Not true in the CV system

Question 25

turbulent flow

Answer 25

1. irregular with eddies and vortices
2. less efficient–requires more pressure to achieve same velocity
   3

Question 26

what promotes turbulent flow?

Answer 26

1. large diameter
2. high velocity
3. low viscosity
4. changes in diameter
5. irregularities on walls

Question 27

turbulent flow produces

Answer 27

shearing forces that can damage vascular endothelium

Question 28

Heartbeat produces:

Answer 28

pulsatile flow in aorta, but pulsatile flow requires more work.

Pulse pressure is dampened in arterial system.

Question 29

in the capillaries, flow is

Answer 29

continuous