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Flashcards in Hemodynamics Deck (41):
1

What do veins function as in the circulatory system?

Capacitors

2

What do arteries function as in the circulatory system?

Resistors

3

Is the arteriole curve of pressure and volume elastic or inelastic?

Inelastic

4

Is the venous curve of pressure and volume elastic or inelastic?

Elastic

5

What layers does an artery have?

1. endothelium
2. Elastic tissue
3. Smooth muscle
4. Fibrous tissue

6

What layers do arterioles have?

Endothelium, and smooth muscle layer

7

What layers do capillaries have?

Endothelial layer

8

What layers do venules have?

Endothelium and fibrous tissue

9

What layers do veins have?

1. endothelium
2. Elastic tissue
3. Smooth muscle
4. Fibrous tissue

10

What is the function of the smooth muscle found in arterioles and venules?

Exert tension during active contraction

11

Why is it important for BP to decrease as it enters capillaries?

To prevent tissue damage

12

The rate of blood flow to an organ or tissue is related to what?

The needs of the organ or tissue

13

CO is controlled by what?

The sum of individual tissue needs

14

Arterial pressure regulation is (in/dependent) of local blood flow or cardiac output control?

Independent

15

What are the units of blood flow?

cm^3/sec

16

What are the units of blood velocity?

cm/sec

17

What are the two ways that arterial pressure is controlled?

Nervous reflexes
Hormones

18

What is ohm law for blood flow?

d(pressure) /R = Flow

19

What is Poiseuille's law for rigid tubes?

Flow = dP(pi)r4 / 8(viscosity)(length)

20

How can you measure viscosity clinically?

taking hematocrit

21

What is anomalous viscosity?

As blood flow decreases, viscosity increases

22

How does blood usually flow? Where is it fastest, and slowest?

In a laminar way (fastest in the inner layer, slowest at the outer layer)

23

What is the effect of laminar flow (what is the shape that it makes)?

Causes a parabolic flow of blood

24

What type of front does turbulent blood flow have?

Squared

25

Why is turbulent flow inefficient?

Have to overcome the resistance to move blood

26

When do you induce turbulent flow?

When listening for Korotkoff sounds

27

Which heart sound is produced from turbulent blood flow?

S4

28

What is Renolds number?

Propensity of fluid to produce a turbulent flow

29

What is the equation for turbulent flow?

Re = 2(radius)(velocity)(ro) / (viscosity)

30

How does vessel flow compare to a rigid tube?

Has a exponential curve, as opposed to a linear one

31

How does no SNS stimulation of vessels compare to high SNA stimulation?

No SNS allows for higher flow rates at lower pressures

(x^2 curve)

32

How does SNS change resistance?

Increases it, which will decrease flow (1/x curve)

33

What is the transmural pressure equation?

Tension = (d pressure)(radius)

34

As vessel radius increases, or blood pressure increases, what happens to wall tension?

increases (Tension = (d pressure)(radius))

35

What is the buffer for changes in wall tension?

Elastic tissue in vessels

36

What happens to the blood flow as it goes through capillaries? Note that flow = (velocity)(CSA).

Flow remains constant. Thus velocity increases if CSA decreases, and vice versa

37

Does the capillary bed have an increase in CSA or decrease relative to arteries? What, then, happens to velocity?

Increased, thus velocity decreases

38

Is blood resistance lower or higher when vessels are run in a series?

Higher (R1 +R2)

39

Is blood resistance lower or higher when vessels are run in parallel?

Lower (1/R1 + 1/R2)

40

Review all the equations

Don't press 5.

41

What is the critical closing pressure?

The point of pressure at which there is infinite resistance