Lecture 09 Overview of Circulation

Question 0

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

Answer 0

Vessel diameter

Question 1

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

Answer 1

Veins

Question 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?

Answer 2

1 PRU

Question 3

Reynolds number is a measure of what parameter?

Answer 3

Tendency for turbulence

Question 4

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

Answer 4

3.0

Question 5

What are the functional parts of the circulation?

Answer 5

Aorta, arteries, arterioles, capillaries, venules and veins

Question 6

What is the arterial pressure during systolic?

Answer 6

120 mm Hg

Question 7

What is the arterial pressure during diastolic period

Answer 7

80 mm Hg

Question 8

When does the arterial pressure drop to 0 mm Hg?

Answer 8

By the time it reaches the termination of the vena cava

Question 9

What is the pressure range of the systemic capillary?

Answer 9

35 mm Hg to 10 mm Hg

Question 10

What is the systolic pulmonary artery pressure?

Answer 10

25 mmHg

Question 11

What is the Pulmonary diastolic pressure?

Answer 11

8 mm Hg

Question 12

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

Answer 12

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

Question 13

What makes up the pulmonary system?

Answer 13

Pulmonary arteries, arterioles, capillaries, venules, pulmonary veins

Question 14

What is the major function of arteries?

Answer 14

Transport under high presssure

Question 15

What do arterioles control?

Answer 15

Conduits

Question 16

What are the functions of capillaries?

Answer 16

Exchange between blood and extracellular fluid

Question 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?

Answer 17

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

Question 18

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

Answer 18

16%

Question 19

What is the equation of velocity of blood flow?

Answer 19

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

Question 20

What is the first principle of the circulatory system?

Answer 20

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

Question 21

What is the second principle of the circulatory system?

Answer 21

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

Question 22

What is the third functional principle of the circulatory system?

Answer 22

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

Question 23

What type of vessels monitor tissue needs?

Answer 23

Microvessels

Question 24

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

Answer 24

Act directly on local blood vessels and dilate or constrict accordingly

Question 25

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

Answer 25

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

Question 26

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

Answer 26

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

Question 27

What are factors that determine blood flow?

Answer 27

``` Pressure difference (pressure gradient) Resistance ```

Question 28

How can the flow through a vessel be calculated?

Answer 28

by Ohm's law F = Change of P/R Change of P = P1-P2 ml/min or liters/min

Question 29

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

Answer 29

5000 ml/min | which is the cardiac output

Question 30

What is laminar blood flow?

Answer 30

Streamline flow in layers

Question 31

What are the characteristics of streamlines?

Answer 31

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

Question 32

When does turbulent flow occur?

Answer 32

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

Question 33

When does blood flow with greater resistance?

Answer 33

When eddy currents occur

Question 34

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

Answer 34

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

Question 35

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

Answer 35

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)

Question 36

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

Answer 36

At Re above 200-400

Question 37

When will turbulence occur even in a straight vessel?

Answer 37

When Re rises above 2000

Question 38

What is blood pressure

Answer 38

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

Question 39

How can pressure be measured?

Answer 39

With a mercury manometer or with electronic transducers