Regulation of Peripheral and Coronary Circulation

Question 1

carotid sinus afferents travel to medulla via

Answer 1

CN IX

Question 2

aortic sinus afferents travel to medulla via

Answer 2

CN X

Question 3

baroreceptors are functional between MAP of

Answer 3

75-150

Question 4

sympathetic stimulation of heart

Answer 4

symptoms stim releases NE to SA and AV, and myocardium

binds to B1 –> G proteins inc cAMP –> inc in If in nodal cells and Ica in all myocardial cells

–> inc rate phase 4 depolarization –> threshold reached sooner which translates to faster HR

–> inc in ICa in non

Question 5

___ contribute the major portion of TPR

Answer 5

arterioles

P drop between small arterioles and capillaries is largest of any segment in the circulation –> 60-70 mmHg

Question 6

3 func of arterioles

Answer 6

1. reduce BP at entrance to capillaries
2. distribution of BF between/within tissues
3. dampens pressure pulses

Question 7

autoregulation of BF at occurs at the ____ level without involvement of the ANS

Answer 7

autoregulated

Question 8

2 mech involved in phenomenon of BF autoregulation

Answer 8

• myogenic mech (stretch activated channels in smc respond to inc P or stretch by allowing Na/Ca influx)
• vasodilator mech (inc BF washes out/removes metabolites otherwise causing dilation –> (adenosine))

Question 9

causes of edema

Answer 9

• inc venous P (inc capillary hydrostatic P)
• dec blood osmotic P (less force pulling H2O into capillaries)
• inc interstitial osmotic P (inc interstitial protein pulls water out of capillaries) exp. inflamm

Question 10

sympathetic stim (___) contracts smc to drive venous return to heart

Answer 10

sympathetic stim (alpha-1) contracts smc to drive venous return to heart

Question 11

How to inc myocardial O2 delivery

Answer 11

inc coronary circulation (already extracting max O2 at rest)

• coronary a. smc innervated by alpha-1 sympathetic n. (constrict coronary a.)
• but AUTOREGULATION w/ ADENOSINE can act as a potent vasodilator that overcomes sympathetic stimulation

Question 12

coronary BF in LV occurs primarily during

Answer 12

diastole

small coronary branches compressed during systole, inc HR dec diastolic interval, impairs flow.