Exam #2: Blood Pressure Regulation

Question 1

What is blood pressure?

Answer 1

Force exerted by the blood against any unit area of the vessel wall

Proportional to Flow x resistance

Question 2

What is the equation for mean arterial pressure?

Answer 2

MAP= CO x TRP

Cardiac output x total peripheral resistance

Question 3

Draw the arterial pressure waveform.

Answer 3

N/A

Question 4

What is the effect of vasoconstriction?

Answer 4

Increased MAP 
Longer DBP (Diastolic runoff) & shallower
Decreased capillary hydrostatic pressure pressure (because constriction is occurring upstream of the capillary, in the arteriole)

Question 5

What is the effect of vasodilation?

Answer 5

Decreased MAP
Shortened DBP (Diastolic runoff) & steeper
Increased capillary hydrostatic pressure

Question 6

What is pulse pressure?

Answer 6

SBP- DBP

Systolic blood pressure - diastolic blood pressure

Question 7

How is MAP estimated?

Answer 7

(1/3 x Pulse pressure) + DBP

Question 8

Review how blood pressure is measured.

Answer 8

1) Cuff inflation & listen to turbulent flow of blood through artery
2) Korotkoff sounds

• Not as accurate as direct cannulation

Question 9

What are the determinants of pulse pressure? How are these augmented pathologically?

Answer 9

Stroke volume output

• PDA
• Aortic regurgitation

Compliance

• Arteriosclerosis
• Aortic stenosis

Systolic ejection

Question 10

Does is pulse wave velocity measured clinically?

Answer 10

Compliance; the pulse wave is inversely proportional to compliance

Slow= compliant 
Fast= rigid

Question 11

As the pulse wave travels down the blood vessel, what happens to the amplitude of the wave?

Answer 11

It gets bigger i.e. it is “amplified” thus, downstream pressure are greater than proximal pressures ?????

Question 12

What does rigidity i.e. reduced compliance do to the amplitude of the pulse wave?

Answer 12

Intensifies it i.e. a larger amplitude= a less compliant aorta

Question 13

What happens to the incisura as you compare arterial waveforms, traveling distally through the vascular tree?

Answer 13

The incisura occurs later in time

“Blip” that occurs from closure of aortic valve

Question 14

What happens to the arterial waveform in regards to the amplitude as you travel down the vascular tree?

Answer 14

Dampen

Especially at the level of the arterioles

Question 15

Why is it good to have large pressure drop-off at the level of the arterioles?

Answer 15

Protection of the capillaries distally

Question 16

What happens to capillary hydrostatic pressure, resistance, & blood velocity (in the capillaries) with constriction of the arterioles?

Answer 16

Decreased capillary hydrostatic pressure
Increased resistance
Decreased blood velocity

Question 17

What happens to capillary hydrostatic pressure, resistance, & blood velocity (in the capillaries) with dilation of the arterioles?

Answer 17

Increased capillary hydrostatic pressure
Decreased resistance
Increased blood velocity

Question 18

Describe the distribution of CO at rest.

Answer 18

High percentage of cardiac output goes to:

1) Liver
2) Kidney
3) Muscles
4) Brain

Question 19

What changes the distribution of cardiac output?

Answer 19

Demand

Question 20

How is the distribution of cardiac output changed?

Answer 20

Local changes in arteriole resistance

Question 21

What is autoregulation?

Answer 21

Maintenance of a stable blood flow, despite increasing arterial pressure

Question 22

What are the mechanisms of autoregulation?

Answer 22

Metabolic mechanism

Myogenic mechanism

Question 23

If there is an increase in pressure, what has to happen to resistance to maintain flow?

Answer 23

Increased resistance

Question 24

What is EDRF?

Answer 24

Nitric Oxide

Question 25

What is the effect of NO on arterioles?

Answer 25

Vasodilation

Question 26

Describe the NO mechanism of action.

Answer 26

Inhibition of MLCK & activation of MLCP

Question 27

Describe the bradykinin mechanism of action.

Answer 27

asdf

Question 28

What is the effect of endothelin?

Answer 28

Vasoconstriction

Question 29

Describe the mechanism of action of endothelin.

Answer 29

Inhibition of MLCP

Question 30

List some other vasoconstrictors.

Answer 30

NE
Angiotensin II
Vasoppressin

Question 31

List the characteristics of short-term (acute) regulation of blood pressure.

Answer 31

• Minutes to seconds
• Change in resistance
• ANS reflex

Question 32

List the characteristics of long-term regulation of blood pressure.

Answer 32

• Days to weeks
• Involves changes in volume
• Renal & hormonal mechanisms

Question 33

What is the effect of sympathetic stimulation of the blood vessels? What is the receptor?

Answer 33

Vasoconstriction

alpha adrenergic recptor

Question 34

What is the effect of sympathetic stimulation of the heart? What is the receptor?

Answer 34

Increased contractility, HR, & conduction velocity

Beta adrenergic receptor

Question 35

What is the effect of sympathetic stimulation of the kidneys? What is the receptor?

Answer 35

Renin release (vasoconstriction via Angiotensin II) 
Decreased GFR (via vasoconstriction) 
Beta adrenergic receptor

Question 36

What is the effect of sympathetic stimulation of the adrenal gland?

Answer 36

Epinephrine & NE release

Question 37

What is the effect of PNS stimulation of the heart?

Answer 37

Muscarinic activation in SA & AV nodes leads to decreased HR

Question 38

When the SNS is stimulated, where is there going to be the greatest change in vascular resistance? Where will the lowest change in vascular resistance be?

Answer 38

Greatest= cutaneous
Smallest= renal

Question 39

What is the effect of vasoconstriction of the arterioles? What is the effect of vasoconstriction of the veins? What is the net effect?

Answer 39

Arterioles= Increased vascular resistance, leading to decreased flow through tissue (more time for metabolism to occur)

Veins= increased venous return to heart