CPR BP regulation and CPR endo Flashcards Preview

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Flashcards in CPR BP regulation and CPR endo Deck (19)
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1
Q

What is the MAP formula?

A
MAP = CO x TPR = HR x SV x TPR
MAP = 2/3(DBP) + 1/3(SBP) b/c heart spends more time in diastole than systole
2
Q

What are the three main systems that regulate MAP?

A

Baroreceptor reflex (rapid)

Renin-angiotensin-aldosterone system (RAAS) (slower)

ADH (vasopressin) and ANP (slower)

3
Q

What are the two main baroreceptor locations?

A

Carotid sinus - CN IX

Aortic sinus - CN X

Both lead to nucleus tractus solitarius (NTS)

4
Q

What are baroreceptors most sensitive to in terms of pressure change?

A

The rate of change more than the magnitude of the change

5
Q

Where is the NTS located?

A

Medulla

6
Q

What does the NTS communicate with to alter BP?

A

Parasympathetic - dorsal motor nucleus of vagus and nucleus ambiguus

Sympathetic - rostral ventrolateral medulla

7
Q

How do the baroreceptors work?

A

Increased frequency of stimulation due to increased stretch for high BP (vice versa for low BP)

8
Q

Is aortic or carotid baroreceptor more sensitive to rate?

A

Carotid more sensitive to rate

Aortic has higher threshold for activation

9
Q

What does the sympathetic NS do in response to decreased baroreceptor firing rate?

A

Constricts arterioles and veins via alpha receptors

Increases HR and contractility via beta 1 receptors

Fluid retention by kidney due to afferent arteriole constriction and renin secretion (later)

10
Q

What does the parasympathetic NS do in response to increased baroreceptor firing rate?

A

Decreases HR, vagus nerve signals SA node via Ach muscarinic receptors

Indirect vasodilation via stimulation of NO release

11
Q

What do baroreceptors do in someone w/ HTN?

A

Reset to be able to regulate pressure at higher set point

12
Q

What hormone systems are in place for longer-term BP adjustments?

A

RAAS

ADH/vasopressin

ANP

13
Q

What is the RAAS? How does it work?

A

Renin-angiotensin-aldosterone system

Regulates blood volume and TPR, overlaps w/ sympathetic system. Renin released by kidney (juxtaglomerular cells) via B1-adrenergic receptor activation. Renin converts angiotensinogen to angiotensin I which is converted to angiotensin II in the lungs/kidneys

14
Q

What does angiotensin II do?

A

Causes secretion of aldosterone from adrenal cortex which causes Na+/H20 retention by kidneys

Stimulates secretion of ADH (reduces urine production, increases H20 retention)

Causes global vasoconstriction of arterioles via AT1 receptors (this increases TPR)

15
Q

What are natriuretic peptides?

A

Induce excretion of Na+ by kidneys which induces excretion of H20

ANP (atrial), BNP (brain), and CNP (c-type)

16
Q

How do natriuretic peptides work?

A

Cause arterioles to dilate to decrease TPR

Increase fluid loss which decreases preload

Inhibits renin which decreases both TPR and preload

Released when excessive preload of atria/ventricles is detected. Protects against overdilation or overstretching of cardiac chambers

17
Q

What happens to the vascular function curve with decreased blood volume?

A

Shifts left

18
Q

What does alpha 1 receptor activation do during aerobic exercise?

A

Constricts vessels to skin, splanchnic regions, kidney, inactive muscle

Dilates vessels at active muscle and coronary circulation

TPR decreases overall

19
Q

What is orthostatic hypotension?

A

Decrease in BP when standing, can cause someone to pass out so blood can get to brain