Flashcards in hemodynamics Deck (29)

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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