Hemodynamics

Question 1

What is the flow equation?

Answer 1

Q=A (v)

Question 2

What type of flow does the below describe?

Q= Q1= Q2= Q3…..

Answer 2

Flow in a series….it is constant

Question 3

What type of flow does the below describe?

Q= Q1+ Q2+ Q3…..

Answer 3

Flow in parallel…it is additive

Question 4

What is blood flow through an INDIVIDUAL organ equivalent to?

Answer 4

It is equivalent to flow through a SERIES

Question 5

Can there be differences in reistance in different organs?

Answer 5

Yes, there can be dramatic differences

Question 6

What is the total peripheral resistance (TPR)?

Answer 6

It is the overall resistance to flow throughout the circulation

Question 7

How are organs arranged in terms of flow?

Answer 7

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

Question 8

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

Answer 8

additive, but in an inverse relationship

Question 9

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

Answer 9

frictional losses from circulation

Question 10

MAP=

Answer 10

CO x TPR

Question 11

CO is approximately equal to what?

Answer 11

Q (resistance)

Question 12

TRP=

Answer 12

P aorta - P r. atrium
_______________
CO

Question 13

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

Answer 13

Decreases= during exercise
Increases= during hypertension

Question 14

What is the critical parameter that characterizes flow?

Answer 14

The Reynolds Number

Question 15

What does the Reynolds number take into account?

Answer 15

disruptive forces (numerator) and cohesive forces (denominator)

Question 16

What is viscosity?

Answer 16

A measure of intermolecular attractions in the liquid

It determines the stepness of the velocity gradient

Question 17

When does laminar flow break down?

Answer 17

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

Question 18

In laminar flow, what is flow proportional to?

Answer 18

Change in P

Question 19

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

Answer 19

Laminar Flow

Question 20

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

Answer 20

Silent= Laminar
Sound= Turbulent

Question 21

What are turbulent flow sounds called?

Answer 21

Auscultory sounds

Question 22

What are murmurs?

Answer 22

audible sounds due to vibrations in heart or vessel walls

Question 23

What is an “innocent” cyctolic murmur?

Answer 23

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

Question 24

What is the gravitational pressure equal to?

Answer 24

(density) (gravity) (height)

Question 25

What is mean circulatory pressure?

Answer 25

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

It ia 7 mm Hg

Question 26

Fluids flow from ________ energy to ________ energy.

Answer 26

High energy to low energy

Question 27

What causes static pressure? What causes dynamic pressure?

Answer 27

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

Dynamic pressure is due to kinetic energy

Question 28

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

Answer 28

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

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

Question 29

What are forces parallel to blood flow?

Answer 29

Sheer and Strain

Question 30

What creates sheer stress

Answer 30

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

Question 31

What is sheer stress proportional to?

Answer 31

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

Question 32

What is sheer stress inversely proportional to?

Answer 32

cube of the vessel radius

Question 33

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

Answer 33

the axial layer

Question 34

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

Answer 34

Yes

Question 35

True or False:

Anything that changes the velocity will lead to stress and sheer

Answer 35

True

Question 36

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

Answer 36

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