Autonomic Control of the CV System

Question 1

What does the dicrotic notch on the arterial blood pressure graph below represent?

Answer 1

Relaxation of the left ventricle; blood falls back against the aortic valve before the aortic pressure decreases.

Question 2

What is the equation for mean arterial pressure (MAP)?

Answer 2

MAP = diastolic pressure + 1/3 pulse pressure

OR

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

Question 3

What is pulse pressure?

Answer 3

The difference between systolic & diastolic pressures.

Question 4

What’s a normal systolic blood pressure?

Answer 4

120 mmHg

Question 5

What’s a normal mean arterial blood pressure?

Answer 5

93.3 mmHg

(80 + 40/3)

Question 5

What’s a normal diastolic blood pressure?

Answer 5

80 mmHg

Question 6

What’s a normal pulse pressure? (Systolic - Diastolic)

Answer 6

40 mmHg

(120 - 80 mmHg)

Question 7

What are the bodies 4 major mechanisms to maintain blood pressure within normal limits?

Answer 7

Question 7

What is the S2 or “Dub” heart sound?

Answer 7

Aortic valve opening in left ventricle

Question 7

What is the S1 or “Lub” heart sound?

Answer 7

Mitral/bicuspid valve opening in left ventricle

Question 8

What factors will cause vasodilation?

Answer 8

Question 8

What are the two categories of vascular diameter regulation?

Answer 8

1. Intrinsic - local control
2. Extrinsic - autonomic & endocrine control

Question 9

What factors will cause vasoconstriction?

Answer 9

Question 10

What are neural control inputs & outputs for maintaining blood pressure homeostasis?

Answer 10

Question 11

Parasympathetic innervation & it’s neurotransmitter acetylcholine (ACh) have what affect on blood vessels?

Answer 11

Vasodilation

Question 12

Sympathetic innervation & it’s neurotransmitters norepinephrine & epinephrine have what affect on blood vessels?

Answer 12

Depends on the receptor.

Sympathetic alpha receptors (both 1 & 2) & beta 1 receptor will cause vasoconstriction.

Sympathetic beta 2 receptor will cause vasodilation.

Both receptor types can bind either epinephrine or norepinephrine

Question 13

Which catecholamine is most abundant in the blood stream?

Answer 13

Epinephrine ( 80%).

Norepinephrine only 20 %

Question 13

What afftects on the heart function do inotropy, chronotropy, & dromotropy have?

Answer 13

Inotropy – contractility

Chronotropy – heart rate

Dromotropy – conduction velocity in the AV node

Question 14

How des norepinephrine & epinephrine affect the mean arterial pressure & heart rate?

Answer 14

Question 15

At low or medium plasma epinephrine concentrations, what is the dominant receptor & the effect of blood vessels?

Answer 15

Low/Medium epinephrine concentrations = beta2 receptor dominance = vasodilation

Question 15

At high plasma epinephrine concentrations, what is the dominant receptor & the effect of blood vessels?

Answer 15

High epinephrine concentrations = alpha receptor dominance = vasoconstriction

Question 16

How is mean arterial pressure regulated?

Answer 16

Question 17

Where are the chemoreceptors for the CV system located?

Answer 17

CV system chemoreceptors detect oxygen levels in the blood.

Chemoreceptors are located in bodies.

Question 18

What is the single most important mechanism for providing short-term regulation of arterial pressure?

Answer 18

Arterial baroreceptors

Question 19

Where are the baroreceptors for the CV system located?

Answer 19

Baroreceptors detect pressure changes in the blood.

Baroreceptor are located in the sinuses

Question 20

What maneuvers can affect the baroreceptor reflex?

Answer 20

Question 21

Describe the effects of the baroreceptor reflex response to increased blood pressure.

Answer 21

Question 22

Describe the effects of the baroreceptor reflex response to increased blood pressure.

Answer 22

Question 23

What ions do peripheral chemoreceptors respond to? What about central chemoreceptors?

Answer 23

Question 24

What is the response of chemoreceptor stimulation?

Answer 24

Question 25

What are the two central chemoreceptor reflexes?

Answer 25

Cerebral Ischemcic response ‘Last ditch response” - triggered by brain ischemia (decreased blood flow, BP less than 60 mmHg); causes increased sympathetic outflow, & intense vasoconstriction & cardiac stimulation

Cushing Reflex - triggere by an increase in intracranial pressure (like an intracranial bleed); also causes increases in sympathetic outflow, MAP, bradycardia (low HR), high BP, & irregular respiration (cushing’s triad)

Question 26

What is the brainbridge reflex?

Answer 26

Question 27

Lecture Summary

Answer 27