Coronary Circulation Flashcards Preview

Physiology Block 1- Cardiovascular Physiology > Coronary Circulation > Flashcards

Flashcards in Coronary Circulation Deck (20)
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1
Q

What is the function of coronary circulation?

A

Supply blood flow to meet the demands of the heart

2
Q

What is the blood flow through the left coronary artery during systole?

A

Minimal blood flow

3
Q

Approximately how much of coronary blood flow occurs during systole?

A

About 20%

4
Q

When is blood flow through the left coronary artery maximal?

A

Diastole

5
Q

What is the relationship between oxygen consumption and amount of coronary blood flow?

A

Direct linear relationship

6
Q

What is the % O2 extraction for the heart at resting state?

A

75%

7
Q

What are the four determinants of cardiac work? Which of these is most expensive on O2 consumption?

A

Heart rate, contractility, pressure development, and shortening/ejection of stroke volume; contractility is most expensive

8
Q

Increase in end-diastolic volume will have what effect on coronary blood flow?

A

Increase

9
Q

An increase in cardiac radius will have what effect on coronary blood flow?

A

Increased

10
Q

What are the determinants of coronary blood flow?

A

Perfusion pressure, extravascular compression, metabolism, and neural input

11
Q

What is the working range of perfusion pressures underwhich the heart can autoregulate coronary blood flow?

A

50-140 mmHg

12
Q

In what part of the cardiac cycle is extravascular compression greatest?

A

Systole

13
Q

Where does most of the systolic coronary blood flow go?

A

Epicardium

14
Q

Which layer of heart tissue is most likely to become ischemic first?

A

Endocardium

15
Q

How does metabolism influence control over coronary blood flow?

A

The creation of vasodilator metabolites

16
Q

What are the effects of SNS stimulation on coronary vasculature?

A

Stimulation of alpha receptors–> constriction; stimulation of beta-2 receptors–> dilation; Also SNS increases HR and contractility which increases concetration of vasodilative metabolites

17
Q

What is the effect of PSNS stimulation on coronary?

A

Vasodilation

18
Q

What is the effect of coronary artery disease on coronary blood flow?

A

Plaques decrease radius leading to increased resistance and an increased pressure drop resulting in a lower perfusion pressure on the other side of the plaque

19
Q

How is nitroglycerin helpful in cases of angina?

A

It dilates systemic vessels, decreasing the afterload, increasing the compliance of veins and decreasing venous return. This decreases the work the heart has to do to pump blood by decreasing radius of the heart

20
Q

How can Ca++ channel blockers be helpful in decreasing cardiac ischemia?

A

Decrease contractility of the heart