CV Control 1: Reg. of Arterial Pressure

Question 0

Formula for resistance with fluids?

Answer 0

Resistance = delta Pressure / Flow

Question 1

Systemic arterial pressure is like potential energy that drives perfusion.

Answer 1

Sure.

Question 2

5 things you need in order to regulate arterial pressure? (basic stuff)

Answer 2

Pressure sensors.
Afferent nerves.
Central neural processing center.
Efferent nerves.
Effectors.

Question 3

What’s the formula for systemic vascular resistance (SVR)?

recall the formula for resistance in general

Answer 3

SVR = Mean arterial pressure (MAP) - Right Atrial Pressure (RAP) / Cardiac output (CO)

(this is just R = delta P / Flow)
corrected. I previously had SVR = MAP / CO, which is a valid estimate if RAP is low, which it normally is

Question 4

What’s the unit used for systemic vascular resistance (SVR)?

Answer 4

Wood units: mmHg / (L / min)

18ish is a normal value.

Question 5

3 short-term blood pressure sensors?

Answer 5

Arterial (carotid bodies and aortic bodies)
Atrial
Ventricular (poorly understood)

Question 6

What are the afferent nerves for the carotid bodies / aortic bodies?
Efferent nerves?

Answer 6

Afferent: CN IX and X
Efferent: autonomics to heart and vasculature

Question 7

What do atrial baroreceptors do in response to increased distension?

Answer 7

Release natriuretic peptides -> renal Na+ and H2O excretion -> lowered BP and volume.

Question 8

What’s the main long-term baroreceptor?

What does detect, and how does it respond?

Answer 8

Juxtoglomerular apparatus.
In response to low blood pressure, it releases renin -> (several steps) -> angiotensin II -> vasoconstriction and Na+ / H2O retention.

Question 9

Significance of ventricular baroreceptors? (not important)

Answer 9

Afferents = CN X, efferents = autonomics.

Low volume may cause these baroreceptors to trigger vasovagal response -> syncope…. but… unclear.

Question 10

What are the gas pedal and the brakes on the heart? Effects?

Answer 10

Gas pedal: beta adrenergic (direct neural or circulating catecholamines) -> increased SA rate, AV rate, and ventricle inotropic state.
Brakes: muscarinic receptors -> decreased SA and AV rates.

Question 11

What parameter is the major determinant of systemic vascular resistance?

Answer 11

Arteriolar diameter.

Question 12

Review: How do different vascular beds respond differently to catecholamines?

Answer 12

alpha adrenergic receptors -> vasoconstriction of renal, cutaneous, and mesenteric vascular beds.
beta adrenergic receptors -> vasodilation of skeletal muscle vascular beds.

Question 13

3 major vasodilators?

Which is most important, and how is it released?

Answer 13

Adenosine, prostacyclin, and NO.
Adenosine is most important, and is released in response to local metabolic activity. (i.e. blood flows where O2/fuel is needed… makes sense)

Question 14

2 ways the kidney reduces total systemic volume?

Answer 14

Pressure diuresis.

Natriuretic peptides from the atria.

Question 15

3 types of natriuretic peptide?

Answer 15

Atrial natriuretic peptide (ANP).
Brain-type natriuretic peptide (BNP - a silly misnomer. nothing to do with brain).
C-type natriuretic peptide (CNP).

Question 16

What’s the most important natriuretic peptide for actual natriuresis?

Answer 16

Atrial natriuretic peptide.

Question 17

What’s the significance of brain-type natriuretic peptide (BNP)?

Answer 17

Clinically, it can be measured to assess heart stress.

It’s released in response to stretching.

Question 18

Where does 40% of the total blood volume usually reside?

How can this be altered?

Answer 18

Normally, 40% of blood volume is in large veins.
Adrenergic signaling -> venomotor constriction -> more preload and blood in central circulation.
Muscarinic signaling -> venomotor relaxation -> less preload.

Question 19

How does your body know to raise BP when you stand up?

Answer 19

Carotid baroreceptors.

these also induce similar changes in response to hemorrhage, though the changes are likely of greater magnitude