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Flashcards in Hemodynamics Deck (36):
1

What is the flow equation?

Q=A (v)

2

What type of flow does the below describe?

Q= Q1= Q2= Q3.....

Flow in a series....it is constant

3

What type of flow does the below describe?

Q= Q1+ Q2+ Q3.....

Flow in parallel...it is additive

4

What is blood flow through an INDIVIDUAL organ equivalent to?

It is equivalent to flow through a SERIES

5

Can there be differences in reistance in different organs?

Yes, there can be dramatic differences

6

What is the total peripheral resistance (TPR)?

It is the overall resistance to flow throughout the circulation

7

How are organs arranged in terms of flow?

In a parallel network (note however, the flow through an individual organ is a series flow)

8

How does the resistance of each organ contribute to the TPR?

additive, but in an inverse relationship

9

What do pressure differences between the aortic valve and the RA come from?

frictional losses from circulation

10

MAP=

CO x TPR

11

CO is approximately equal to what?

Q (resistance)

12

TRP=

P aorta - P r. atrium
_______________
CO

13

Resistance decreases in what condition and increases in what other condition?

Decreases= during exercise
Increases= during hypertension

14

What is the critical parameter that characterizes flow?

The Reynolds Number

15

What does the Reynolds number take into account?

disruptive forces (numerator) and cohesive forces (denominator)

16

What is viscosity?

A measure of intermolecular attractions in the liquid

It determines the stepness of the velocity gradient

17

When does laminar flow break down?

When velocity reaches a critical point (exceeds the Reynolds number)...resistance increase

18

In laminar flow, what is flow proportional to?

Change in P

19

For the same Change in P, which has more flow....turbulent or laminar?

Laminar Flow

20

Which type of flow is silent and which flow generates a sound?

Silent= Laminar
Sound= Turbulent

21

What are turbulent flow sounds called?

Auscultory sounds

22

What are murmurs?

audible sounds due to vibrations in heart or vessel walls

23

What is an "innocent" cyctolic murmur?

occurs when cardiac output increases during excercise which causes turbulent aortic flow during systole

24

What is the gravitational pressure equal to?

(density) (gravity) (height)

25

What is mean circulatory pressure?

the equilibrium pressure that would result throughout the cardiovascular systen if the heart stopped beating.

It ia 7 mm Hg

26

Fluids flow from ________ energy to ________ energy.

High energy to low energy

27

What causes static pressure? What causes dynamic pressure?

Static pressure is coposed of the applied or lateral pressure and force of gravity

Dynamic pressure is due to kinetic energy

28

If the energy is constant for blood flowing in a segment of a vessel what are two important conclusion?

1- As velocirt decreasesm dynamic pressure becomes a smaller fraction of the total pressure

2- As vessel radius narrows, the dynamic component increases significantly

29

What are forces parallel to blood flow?

Sheer and Strain

30

What creates sheer stress

Flowing blood on the endothelial wall directed along to long axis of the vessel

31

What is sheer stress proportional to?

The viscosity and the sheer rate (rate at which the axial velocity changes from the wall to the lumen) and the flow rate

32

What is sheer stress inversely proportional to?

cube of the vessel radius

33

In a blood vessel, which area has the minimal frictional retardation and maximal velocity?

the axial layer

34

Is sheer stress involved in endotheliam cell signalling and the development of atherosclerosis?

Yes

35

True or False:

Anything that changes the velocity will lead to stress and sheer

True

36

In constriction of an artery, what type of pressure decreases and what type of pressure increases?

Lateral pressure decreases and dynamic pressure increases.

This is because whenever blood velocity increases, a greater proportion of the blood pressure is converted from lateral into dynamic pressure