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

What is the MAP formula?

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

What are the three main systems that regulate MAP?

Baroreceptor reflex (rapid)

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

ADH (vasopressin) and ANP (slower)

3

What are the two main baroreceptor locations?

Carotid sinus - CN IX

Aortic sinus - CN X

Both lead to nucleus tractus solitarius (NTS)

4

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

The rate of change more than the magnitude of the change

5

Where is the NTS located?

Medulla

6

What does the NTS communicate with to alter BP?

Parasympathetic - dorsal motor nucleus of vagus and nucleus ambiguus

Sympathetic - rostral ventrolateral medulla

7

How do the baroreceptors work?

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

8

Is aortic or carotid baroreceptor more sensitive to rate?

Carotid more sensitive to rate

Aortic has higher threshold for activation

9

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

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

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

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

Indirect vasodilation via stimulation of NO release

11

What do baroreceptors do in someone w/ HTN?

Reset to be able to regulate pressure at higher set point

12

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

RAAS

ADH/vasopressin

ANP

13

What is the RAAS? How does it work?

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

What does angiotensin II do?

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

What are natriuretic peptides?

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

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

16

How do natriuretic peptides work?

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

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

Shifts left

18

What does alpha 1 receptor activation do during aerobic exercise?

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

Dilates vessels at active muscle and coronary circulation

TPR decreases overall

19

What is orthostatic hypotension?

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