CV Control 1: Reg. of Arterial Pressure Flashcards Preview

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Flashcards in CV Control 1: Reg. of Arterial Pressure Deck (20)
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Systemic arterial pressure is like potential energy that drives perfusion.



Formula for resistance with fluids?

Resistance = delta Pressure / Flow


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

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


What's the formula for systemic vascular resistance (SVR)?
(recall the formula for resistance in general)

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**


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

Wood units: mmHg / (L / min)
18ish is a normal value.


3 short-term blood pressure sensors?

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


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

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


What do atrial baroreceptors do in response to increased distension?

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


What's the main long-term baroreceptor?
What does detect, and how does it respond?

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


Significance of ventricular baroreceptors? (not important)

Afferents = CN X, efferents = autonomics.
Low volume may cause these baroreceptors to trigger vasovagal response -> syncope.... but... unclear.


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

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.


What parameter is the major determinant of systemic vascular resistance?

Arteriolar diameter.


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

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


3 major vasodilators?
Which is most important, and how is it released?

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)


2 ways the kidney reduces total systemic volume?

Pressure diuresis.
Natriuretic peptides from the atria.


3 types of natriuretic peptide?

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


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

Atrial natriuretic peptide.


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

Clinically, it can be measured to assess heart stress.
It's released in response to stretching.


Where does 40% of the total blood volume usually reside?
How can this be altered?

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.


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

Carotid baroreceptors.
(these also induce similar changes in response to hemorrhage, though the changes are likely of greater magnitude)