Lecture 09 Overview of Circulation Flashcards Preview

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Flashcards in Lecture 09 Overview of Circulation Deck (40):
0

84% of the blood volume is in the systemic circulation. Of this, 64% is in what type of vessel?

Veins

1

Blood flow resistance is indirectly proportional to which of the following?
Viscosity
Vessel diameter
Density
Viscosity and density

Vessel diameter

2

If rate of blood flow through the entire circulatory system (cardiac output) = 100ml/sec AND the pressure difference from the systemic arteries to the systemic veins = 100 mmHG, what is the total peripheral resistance equal to?

1 PRU

3

Reynolds number is a measure of what parameter?

Tendency for turbulence

4

What represents the viscosity of blood with a hematocrit of 38-42?

3.0

5

What are the functional parts of the circulation?

Aorta, arteries, arterioles, capillaries, venules and veins

6

What is the arterial pressure during systolic?

120 mm Hg

7

What is the arterial pressure during diastolic period

80 mm Hg

8

When does the arterial pressure drop to 0 mm Hg?

By the time it reaches the termination of the vena cava

9

What is the pressure range of the systemic capillary?

35 mm Hg to 10 mm Hg

10

What is the systolic pulmonary artery pressure?

25 mmHg

11

What is the Pulmonary diastolic pressure?

8 mm Hg

12

What parts of the circulatory system make up the systemic system?

Aorta, large arteries, small arteries, arterioles, capillaries, venules, small veins, large veins, vena cava

13

What makes up the pulmonary system?

Pulmonary arteries, arterioles, capillaries, venules, pulmonary veins

14

What is the major function of arteries?

Transport under high presssure

15

What do arterioles control?

Conduits

16

What are the functions of capillaries?

Exchange between blood and extracellular fluid

17

84% of blood volume is in the systemic circulation. How much of this blood volume is in the veins, arteries and systemic arterioles/capillaries?

64% in veins
13% in arteries
7% in systemic arterioles and capilaries

18

How much % of blood is in the heart and lungs?

16%

19

What is the equation of velocity of blood flow?

V = F/A
F = volume of blood flow
A = vascular cross-sectional area

20

What is the first principle of the circulatory system?

Rate of blood flow to each tissue of the body is almost always precisely controlled in relation to the tissue need

21

What is the second principle of the circulatory system?

The cardiac output is controlled mainly by the sum of all the local tissue flows

22

What is the third functional principle of the circulatory system?

Arterial pressure regulation is generally independent of either local blood flow control or cardiac output control

23

What type of vessels monitor tissue needs?

Microvessels

24

What do O2, other nutrients, CO2 accumulation, tissue wast product accumulation all do to local blood vessels?

Act directly on local blood vessels and dilate or constrict accordingly

25

What does the heart respond to in the second functional principle?

Demands of tissues. And nerve signals may be needed to help the heart pump required amount of blood

26

If arterial pressure falls below 100 mm Hg, nervous reflexes:

Increase force of heart pumping
Constrict large venous reservoirs
Generally constrict most of the arterioles throughout the body (increases arterial pressure)
Kidneys may later play important role in pressure control

27

What are factors that determine blood flow?

Pressure difference (pressure gradient)
Resistance

28

How can the flow through a vessel be calculated?

by Ohm's law
F = Change of P/R
Change of P = P1-P2

ml/min or liters/min

29

What is the overall blood flow of an adult at rest?

5000 ml/min
which is the cardiac output

30

What is laminar blood flow?

Streamline flow in layers

31

What are the characteristics of streamlines?

Each layer maintains same distance from vessel wall
Central - most portion of the blood stays in the center
Each layer slips easily past surrounding layers
Velocity of fluid flowing in center is greater than that of fluid flowing towards the outer edge

32

When does turbulent flow occur?

When flow is too great
Blood passes an obstruction within the vessel
Blood has to make a sharp turn
Blood passes over a rough surface

33

When does blood flow with greater resistance?

When eddy currents occur

34

What is directly proportional and inversely proportional to the tendency for turbulent flow to increase?

Direct proportion to velocity of blood flow
Direct proportion to the diameter of the vessel
Direct proportion to the density of the blood
Inversely to the viscosity of the blood

35

What is the Reynolds number equation (Measure of the tendency for turbulence to occur)?

Re=(v*d*p)/n
Re= reynolds number
v= mean velocity of blood flow in cm/sec
d = vessel diameter in cm
p = density (normally only slightly greater than 1)
n = viscosity (in poise) (blood viscosity normally = 1/30 poise)

36

When will the turbulent flow occur in some regions of a vessel?

At Re above 200-400

37

When will turbulence occur even in a straight vessel?

When Re rises above 2000

38

What is blood pressure

The force exerted by the blood against any unit area of the vessel wall

39

How can pressure be measured?

With a mercury manometer or with electronic transducers