Unit 4 - Coronary Circulation Flashcards
What is blood flow to the heart supplied by?
left and right coronary arteries
What does the right coronary artery supply?
the majority of supply to the right atrium and ventricle
What does the left coronary artery supply?
the majority of supply to the left atrium, ventricle, and interventricular septum
What do coronary arterioles control?
myocardial O2 supply
What determines the delivery of O2?
flow rate
How is flow rate calculated?
(AoP-RAP)/R
When the heart needs O2, what must happen?
coronary flow must increase
What does insufficient O2 supply for demand lead to?
ischemia
What is coronary microcirculation?
the regulation of coronary arteriolar tone is highly coupled to energy needs of myocardial cells
What has a major role in increased O2 need?
metabolic vasodilation
What can overcome metabolic vasodilation?
neurogenic vasoconstriction
What causes dilation with intact endothelium?
vascular and platelet factors
When does most of the coronary blood flow occur?
during diastole - 85%
What can impair the peak flow rate of coronary circulation?
when myocardial relaxation in early diastole is slowed
Where does ischemia happen first?
in the subendocardium because coronary flow goes from epicardial to endocardial areas
What are some situations that provoke myocardial ischemia?
loss of blood volume, aortic valve does not close entirely, coronary artery disease, insufficient oxygenation of blood, if some disease drives the sinus node faster and faster, disease on the right side of the heart, anything that causes the ventricular muscle to be thicker than normal
When ischemia happens, what is happening in the aorta, and what happens to perfusion pressure?
aortic pressure is diminished and so is perfusion pressure
