Determinants of coronary blood flow

Question 1

What is an extrinsic regulator of coronary blood flow?

Answer 1

The sympathetic nervous system releasing NA

Question 2

What happens to the coronary blood flow when the sympathetic nervous system releases NA?

Answer 2

It binds to the α1- adrenergic receptor which causes vasoconstriction and increased resistance.
It also binds to the β1 adrenergic receptor which causes an increase in heart rate and stroke volume

Question 3

Why is the sympathetic regulator of coronary blood flow not sustainable?

Answer 3

Because when we are exercising, we want to increase blood flow to the heart because there is increased work but yet we are vasoconstricting when we are releasing NA

Question 4

What is the primary regulator of coronary blood flow? Is this an extrinsic or intrinsic regulator?

Answer 4

Metabolic autoregulation

intrinsic

Question 5

Describe the process of metabolic autoregulation that controls vascular diameter

Answer 5

If there is an increase in the metabolic activity of the organ, there is an increase in O2 consumption and this means that O2 decreases, there is an increase in the metabolites in the organ interstitial fluid. This causes arteriolar dilation in the organ and increases blood flow to the organ

Question 5

Describe the process of metabolic autoregulation that controls vascular diameter

Answer 5

If there is an increase in the metabolic activity of the organ, there is an increase in O2 consumption and this means that O2 decreases, there is an increase in the metabolites in the organ interstitial fluid. This causes arteriolar dilation in the organ and increases blood flow to the organ

Question 6

What are three vasodilator messengers that regulate coronary blood flow?

Answer 6

adenosine, NO, hypoxia

Question 7

What is the effect of adenosine?

Answer 7

Adenosine comes from the breakdown of ATP to AMP. It binds to its adenosine receptor and causes coronary vasodilation

Question 8

What is the effect of NO on the coronary blood flow?

Answer 8

NO is released from the endothelium and this relaxes the smooth muscle cells which causes vasodilation. This leads to decreased resistance and increased blood flow.

Question 9

What is the effect of hypoxia on coronary blood flow?

Answer 9

It causes vasodilation