hemodynamics Flashcards Preview

CV exam 1 wk 1 > hemodynamics > Flashcards

Flashcards in hemodynamics Deck (29):
1

pressure

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

2

volume

1. Total blood volume ~ 5 L
2. Largest volume in veins (“capacitance vessels”)

3

flow equation

Q= ΔP/ R

Q: blood flow
P: pressure
R: resistance

4

flow in must equal

flow out

the total flow is constant throughout the CV system

5

Flow (Q)

volume per unit time (ml/min)
CONSTANT through system (since closed loop)

6

cardiac output (CO) =

(Pa - Pv) / TPR

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

7

V (Velocity) =

Q/A

8

velocity is highest in the

aorta (lowest total cross sectional area

9

velocity is lowest in the

capillaries (greatest cross sectional area)

10

what is the cardiac output?

the volume of blood pumped per minute by the heart
5L/min at rest

11

Cardiac output corresponds to the

total flow in the cardiovascular system

12

poiseuelle's Equation

Q = ΔP x (π r^4)/8nl

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

13

if you increase radius?

decrease R and increase Q

14

if you increase viscosity?

increase R and thus decrease Q

15

if you increase length?

increase R and thus decrease Q

16

what is the biggest determinant of flow?

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

17

Resistance in parallel

decreases the total resistance

18

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

lower

19

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

little effect on the whole system

20

the total resistance in the capillary beds is

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

21

resistance in a series is

additive
Rf= R1 + R2 + R3 + ...

22

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

higher

23

blood flow through a series is

constant, but the pressure drops

24

laminar flow

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

25

turbulent flow

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

26

what promotes turbulent flow?

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

27

turbulent flow produces

shearing forces that can damage vascular endothelium

28

Heartbeat produces:

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

Pulse pressure is dampened in arterial system.

29

in the capillaries, flow is

continuous