Hemodynamics Flashcards Preview

Physiology > Hemodynamics > Flashcards

Flashcards in Hemodynamics Deck (41)
Loading flashcards...
1
Q

What do veins function as in the circulatory system?

A

Capacitors

2
Q

What do arteries function as in the circulatory system?

A

Resistors

3
Q

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

A

Inelastic

4
Q

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

A

Elastic

5
Q

What layers does an artery have?

A
  1. endothelium
  2. Elastic tissue
  3. Smooth muscle
  4. Fibrous tissue
6
Q

What layers do arterioles have?

A

Endothelium, and smooth muscle layer

7
Q

What layers do capillaries have?

A

Endothelial layer

8
Q

What layers do venules have?

A

Endothelium and fibrous tissue

9
Q

What layers do veins have?

A
  1. endothelium
  2. Elastic tissue
  3. Smooth muscle
  4. Fibrous tissue
10
Q

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

A

Exert tension during active contraction

11
Q

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

A

To prevent tissue damage

12
Q

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

A

The needs of the organ or tissue

13
Q

CO is controlled by what?

A

The sum of individual tissue needs

14
Q

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

A

Independent

15
Q

What are the units of blood flow?

A

cm^3/sec

16
Q

What are the units of blood velocity?

A

cm/sec

17
Q

What are the two ways that arterial pressure is controlled?

A

Nervous reflexes

Hormones

18
Q

What is ohm law for blood flow?

A

d(pressure) /R = Flow

19
Q

What is Poiseuille’s law for rigid tubes?

A

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

20
Q

How can you measure viscosity clinically?

A

taking hematocrit

21
Q

What is anomalous viscosity?

A

As blood flow decreases, viscosity increases

22
Q

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

A

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

23
Q

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

A

Causes a parabolic flow of blood

24
Q

What type of front does turbulent blood flow have?

A

Squared

25
Q

Why is turbulent flow inefficient?

A

Have to overcome the resistance to move blood

26
Q

When do you induce turbulent flow?

A

When listening for Korotkoff sounds

27
Q

Which heart sound is produced from turbulent blood flow?

A

S4

28
Q

What is Renolds number?

A

Propensity of fluid to produce a turbulent flow

29
Q

What is the equation for turbulent flow?

A

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

30
Q

How does vessel flow compare to a rigid tube?

A

Has a exponential curve, as opposed to a linear one

31
Q

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

A

No SNS allows for higher flow rates at lower pressures

x^2 curve

32
Q

How does SNS change resistance?

A

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

33
Q

What is the transmural pressure equation?

A

Tension = (d pressure)(radius)

34
Q

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

A

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

35
Q

What is the buffer for changes in wall tension?

A

Elastic tissue in vessels

36
Q

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

A

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

37
Q

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

A

Increased, thus velocity decreases

38
Q

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

A

Higher (R1 +R2)

39
Q

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

A

Lower (1/R1 + 1/R2)

40
Q

Review all the equations

A

Don’t press 5.

41
Q

What is the critical closing pressure?

A

The point of pressure at which there is infinite resistance