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Flashcards in Cardiovascular control Deck (42)
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1

What is ANP?

Atrial natriuretic peptide. Released from atrial myocytes in response to  increased blood volume and atrial pressure. Acts via cGMP.

2

What does ANP cause?

Causes vasodilation and  decreased Na
+ reabsorption at the renal collecting tubule. Dilates afferent renal arterioles (in) and constricts efferent arterioles (out), promoting diuresis and contributing to “aldosterone escape” mechanism.

3

What is BNP?

Released from ventriculate myocytes in response to increased tension. Similar physiologic mech to ANP. Longer half life.

4

What can BNP be used to diagnose?

HF.

5

What three kinds of sensors in the cardiovascular system are involved in short term responses?

Arterial baroeceptors, atrial baroreceptors, ventricular baroreceptors.

6

Where are arterial baroreceptors located?

At carotid sinus and aortic arch.

7

What causes arterial baroreceptors to fire?

Cationic channels that response to stretch; open and firing more when stretched ie when pressure is increased.

8

Are arterial baroreceptors more responsive to pulsatile changes or static changes?

Pulsatile changes. If pressure increases slowly and is maintained at a new high, firing rate of baroreceptors decline back towards baseline causing resetting.

9

What is the afferent pathway of aortic arch baroreceptors?

Afferent = out = via vagus nerve to solitary nucleus of medulla.

10

What is the afferent pathway of carotid sinus baroreceptors?

Afferent = out = via glossopharyngeal (IX) nerve to solitary nucleus of the medulla.

11

What is the efferent pathway of the baroreceptor reflexes?

Efferents modulate sympathetic/parasympathetic firing at heart and blood vessels.

12

How does hypotension elicit baroreceptor response?

Decr arterial pressure, decreased stretch, decreased afferent baroreceptor firing. This leads to increased efferent SYMPATHETIC firing and decreased PARASympathetic stimulation. Result is vasoconstriction, incr HR, Incr contractility, Incr BP.

13

How does carotid massage elicit baroreceptor response?

Incr pressure on carotid sinus, increase stretch, increased afferent baroreceptor firing, Increased parasympathetic activity, increased AV node refractory period, decrease HR.

14

Quick review, why would carotid massage lead to increased AV node refractory period?

Increased vagal tone = increased Ach. Ach binds to G-coupled protein on pacemaker cell membrane, alpha subunit interacts w/ K+ channel, allowing greater K+ efflux from pacemaker cell, thus making cell more negative and farther from threshold. Slower to reach activation = HR goes down.

15

Where are chemoreceptors located?

Peripherally in the carotid sinus and aortic arch. Central ones as well.

16

What do peripheral chemoreceptors respond to?

Stimulated by drop in pO2 (<60), rise in pCO2, and decrease in pH of blood.

17

What do peripheral chemoreceptors do when stimulated?

Primarily concerned with respiration, but increased firing also leads to communication with medulla that leads to increased adrenergic output --> increased BP.

18

What do central chemoreceptors respond to?

Just changes in pH and pCO2 of brain interstitial fluid, which are influenced by arterial pCO2. Do not directly response to pO2.

19

What is the cushing reaction?

Triad of hypertension, bradycardia, and respiratory depression.

20

What is the sequence of events causing the cushing reaction?

Increased intracranial pressure constricts arterioles, leading to cerebral ischemia. This increases pCO2 and decreases pH. Central chemoreceptors increase sympathetic output, leading to HTN. The stretch effect on the baroreceptors causes peripheral baroreceptor-induced bradycardia.

21

What is normal right atrial pressure?

<5

22

What is normal right ventricular pressure?

25/5

23

What is normal pulmonary artery pressure?

25/10

24

What is normal pulmonary capillary wedge pressure? What is it a good approximation of?

<12. Good approximation of left atrial pressure.

25

What is normal left atrial pressure?

<12

26

What is normal left ventricular pressure?

130/10

27

What is normal aortic pressure?

130/90

28

In what context would you see PCWP > LV diastolic pressure

Mitral stenosis

29

What local metabolites have a vasodilatory effect on the blood vessels supplying the heart?

adenosine, NO, CO2, Decr O2.

30

What local metabolites have a vasodilatory effect on the vessels supplying the brain?

CO2 (pH)