5.1 Special circulations

Question 1

In general what do the right and left coronary supply?

Answer 1

right: RV and RA
left: LV and LA
- left supplies a larger proportion usually

Question 2

What is the venous drainage of the heart

Answer 2

drain into the coronary sinus which opens up directly into the ventricles

Question 3

when is flow in the left coronary lowest and highest?

Answer 3

low: early systole as the contraction compresses the vessel
high: diastole - the relaxed ventricles no longer compress the vessel
Impacted in tachycardia as diastolic time decreases and wont be able to fully perfuse

Question 4

what happens to the flow in the right coronary artery and why?

Answer 4

resembles that in the aorta with systole producing a larger contribution. There is lower wall tension in the right heart as it pumps against the lower resistance pulmonary circulation

Question 5

what is the metabolic control of coronary resistance?

Answer 5

as cardiac work increases, metabolism increases and there is a drop in ATP which is sensed by ATP gated channels, relaxing the vessel (vasodilation) and allowing more perfusion
also senses NO and Adenosine

Question 6

role of Katp channels in vasodilation of coronary vessels

Answer 6

when ATP production decreases this will activate the K channels
This will lead to hyperpolarization of VSMC - calcium decreases and vasodilation will occur

Question 7

Role of adenosine in vasodilation of coronary vessels

Answer 7

transiently released from myocardial cells, activates adenosine receptors and K atp channels - vasodilation
this will also enhance the release of NO

Question 8

Role of NO in vasodilation of coronary vessels

Answer 8

relaxes smooth muscle cells

Question 9

what is the main determinant of cerebral blood flow?

Answer 9

pCO2