12.2 B

Question 1

How does the mean arterial pressure in the various organs differ from one another?

Answer 1

they all have the same pressure differential (MAP-RAP)

Question 2

Given that the pressure differential across each organ is the same, what accounts for the variability in flow across each?

Answer 2

differences in resistance

Question 3

What is pulse pressure?

Answer 3

the systolic pressure minus the diastolic pressure

Question 4

What is the runoff phase?

Answer 4

the part of the cardiac cycle in which blood is only leaving the arteries

Question 5

What is the main factor determining the rate of blood leaving the arterial system (runoff)?

Answer 5

arteriolar resistance (TPR)

Question 6

How can we calculate MAP from systole and diastole?

Answer 6

MAP = diastolic pressure + (1/3 systolic pressure)

Question 7

Diastolic arterial pressure is determined by what factors?

Answer 7

• rate of runoff

- duration of runoff

Question 8

What happens to runoff when systemic arteries are dilated?

Answer 8

TPR is decreased, flow increases, runoff increases, arterial diastolic pressure decreases

Question 9

Diastolic arterial pressure can be increased by doing what two things?

Answer 9

• increasing TPR via arteriolar constriction

- increasing heart rate

Question 10

What are the three determinants of arterial systolic pressure?

Answer 10

• ejection rate
• stroke volume
• arterial compliance

Question 11

How does aortic stenosis affect the arterial systolic pressure?

Answer 11

• stenosis decreases ejection rate

- pressure is reduced in the arteries

Question 12

Increased stroke volume will do what to arterial systolic pressure?

Answer 12

increase it

Question 13

Decreased arterial compliance will do what to arterial pressure?

Answer 13

increase systolic arterial pressure

Question 14

How is compliance mathematically defined?

Answer 14

compliance = (volume change)/(pressure change) = (stroke volume)/(pulse pressure)

Question 15

If pulse pressure is different between two people, it can likely be attributed to what?

Answer 15

a difference in stroke volume

Question 16

If pulse pressure changes in an individual over a short period of time, it can be attributed to what?

Answer 16

either a change in stroke volume or a change in complicance

Question 17

What happens to diastolic arterial pressure when compliance is reduced?

Answer 17

it drops more quickly and reaches a lower value

Question 18

Which blood vessels have the lowest velocity of blood flow?

Answer 18

capillares

Question 19

How, if cardiac output must equal the flow through the whole system, do capillaries have slow flow?

Answer 19

because taken all together, capillaries have the most cross sectional area of any set of vessels

Question 20

Most blood is found in which part of the system?

Answer 20

systemic veins

Question 21

A small change in blood volume will have what effect on pressure in the veins versus the arteries?

Answer 21

with increased compliance, an increase in blood volume has little change on the pressure within veins

Question 22

Why does venous constriction/dilation have little effect on venous resistance?

Answer 22

because the radius only changes slightly

Question 23

Venous constriction significantly increases _____ without significantly altering _____. This allows for what?

Answer 23

• pressure without significantly altering resistance

- allowing for increased venous return with venous constriction

Question 24

How are centimeters of water converted to mm Hg?

Answer 24

centimeters x 1.36.

Question 25

What is an example of series resistance in the human body?

Answer 25

TPR

Question 26

What is an example of parallel resistance in the human body?

Answer 26

resistance in the organs

Question 27

TPR is (lower/higher) than the lowest organ vascular resistance?

Answer 27

lower since the organs are in parallel

Question 28

What is the conversion rate for mm Hg to dynes?

Answer 28

mm Hg x 1330

Question 29

What is a normal value of TPR?

Answer 29

1 mm Hg/ml/sec

Question 30

Poiseuille’s law says what about resistance?

Answer 30

that a small decrease in radius will greatly increase the resistance of a tube

Question 31

Poiseuille’s law says what about viscosity?

Answer 31

as viscosity increases, so does resistance of a tube

Question 32

Viscosity of blood is largely determined by what?

Answer 32

the erythrocyte concentration (hematocrit)

Question 33

What happens to the rate of flow when that flow becomes turbulent?

Answer 33

flow decreases

Question 34

Turbulent blood flow is more likely if what changes?

Answer 34

• flow increases
• viscosity decreases
• vessel radius decreases

Question 35

What happens to resistance of flow when that flow becomes turbulent?

Answer 35

it greatly increases

Question 36

Sphygmomanometers function on the basis of what hemodynamic factor?

Answer 36

turbulent blood flow due to arterial collapse under the pressure of the cuff

Question 37

What is an ankle brachial index?

Answer 37

• use doppler to identify systolic pressure in the leg

- systolic in leg/systolic in brachial artery should be between 1 and 1.4

Question 38

If the ankle brachial index is below 1, it is indicative of what?

Answer 38

large plaques in the arteries to the legs or coarctation of the aorta

Question 39

What is the skeletal muscle pump?

Answer 39

the idea that muscle contraction is used to drive blood flow in the veins

Question 40

Inspiration does what to venous return?

Answer 40

increases venous return to the right heart

Question 41

Inspiration has what effect on the left heart?

Answer 41

• pulmonary veins distend
• pressure in pulmonary veins decreases
• flow is diminished
• return to left atrium decreases

Question 42

Expiration will do what to the immediate heart rate?

Answer 42

it slows it slightly as pulmonary vein return to the left heart increases and stroke volume increases

Question 43

How does arterial pressure change during the valsalva maneuver?

Answer 43

• it initially increases as stroke volume in the left heart increases
• continued increased intrathoracic pressure decreases venous return
• eventually arterial pressure drops as less blood becomes available to the left heart

Question 44

What happens to venous return when central venous pressure increases?

Answer 44

return decreases since the pressure differential in the venous system decreases

Question 45

What happens to ventricular filling when central venous pressure increases?

Answer 45

ventricular filling increases

Question 46

A venous function curve puts what to lines on a graph?

Answer 46

1) venous return and 2) cardiac output as functions of central venous pressure

Question 47

Where is the steady state on a venous function curve?

Answer 47

where the two curves intersect and venous return equals cardiac output