Nov15 M2-Coronary Circulation

Question 1

epicardial vs intramural coronaries

Answer 1

intramural enter within wall. squeezed when contraction

Question 2

arrhythmias main cause chemically

Answer 2

accum of waste products

Question 3

2 organs that don’T store nutrients

Answer 3

heart and brain

Question 4

what phase of cardiac cycle LV perfused + explanation of problems in exercise

Answer 4

in diastole. shortneed in exercise bc faster HR so coronary problems

Question 5

organs with good flow autoregulation and goal of that

Answer 5

heart, brain, kidney.

if BP drops, bring it back to normal

Question 6

how flow autoregulation works

Answer 6

dilation of small arteries and arterioles to bring R down

Question 7

range of autoregulation in CPP (coronary perfusion pressure)

Answer 7

big range. 35-200 mmHg

Question 8

2 components of flow autoregulation

Answer 8

metabolic and myogenic

Question 9

metabolic comp of flow autoregulation

Answer 9

less O2 and more metabolites when BP drop makes the SM relax

Question 10

myogenic comp of flow autoregulation

Answer 10

decreased stretch of SM bc BP drop makes it relax

Question 11

Bayliss effect def

Answer 11

myogenic comp of flow autoregulation

Question 12

what happens if increase BP and stretch across arteriole in Bayliss effect

Answer 12

SM constricts

Question 13

2 problems in ATS

Answer 13

plaque that clogs arteries

endothelial dysfunction

Question 14

twin epidemic in US: what 2 diseases

Answer 14

diabetes and obesity

Question 15

endothelial dysfunction def

Answer 15

imbalance between vasodilating and vasoconstricitng substances produced by endoth

Question 16

risk factors for endoth dysf

Answer 16

same as ats (age, fam history, smoking, diabetes, obesity, LDL, htn, )

Question 17

what’s found on endothelium

Answer 17

multiple receptors (muscarinic, bradykinin, thromboxane, etc.)

Question 18

2 substances produced by endothelium and important one

Answer 18

NO (important) (vasodilative) and endothelin (vasoconstrictive)

Question 19

NO 3 effects

Answer 19

vasoactive (makes SM relax)
antiproliferative on SM (atheroprotective)
antithrombotic: acts on clotting cascade

Question 20

what regulates NO prod

Answer 20

compounds binding to endothelium receptors

Question 21

NO producing enzyme

Answer 21

eNOS (endoth NO synthase)

Question 22

flow-dependent vasodilation: what

Answer 22

as increase perfusion P across vessel, flow increases but transmural P unchanged

Question 23

how flow-dependent vasodilation works

Answer 23

flow leads to NO production by endoth.

makes SM relax

Question 24

Ach effect on dilation

Answer 24

makes endothelium produce NO to relax SM

Question 25

Ach testing capacity

Answer 25

if transmural P doesn’t drop due to Ach, means endoth dysfct

Question 26

htn effect on endoth fct and expected Ach response

Answer 26

causes endoth dysfct. poorer Ach response

Question 27

Ach normally in the blood

Answer 27

none

Question 28

Ach effect if complete endoth dysfct

Answer 28

CONSTRICTION of vessels bc of muscarinic receptor on SM

Question 29

normal Ach effect on vessel if inject it (2)

Answer 29

make endoth produce NO. NO greater effect than Ach on SM

Question 30

3 organs with most O2 consumption on order

Answer 30

heart, kidney, brain

Question 31

Fick’s principle

Answer 31

O2 consumption of organ = flow to that organ x arterio-venous O2 diff

Question 32

how AV O2 difference changes with exercise

Answer 32

doesn’t change. O2 demand met with increased blood flow

Question 33

coronary flow reserve + normal

Answer 33

CFR = max coronary flow div. resting coronary flow.

young healthy is 5

Question 34

EXAM: 3 determinants of O2 consumption in the heart

Answer 34

HR, contractility, wall stress

Question 35

wall stress

Answer 35

tension in wall. determined by preload (EDV) and afterload (aortic BP)

Question 36

rate-pressure product def + how changes with exercise

Answer 36

HR x BP.

increases linearly with O2 consumption