Special Circulation

Question 1

What do the Right & left coronary arteries arise from?

Answer 1

base of aorta

Question 2

Where does most coronary venous blood drain?

Answer 2

via coronary sinus into the right atrium

Question 3

How can extra 02 be supplied?

Answer 3

only be supplied by increasing coronary blood flow

Question 4

What intrinsic mechanisms control coronory blood flow?

Answer 4

Decreased Po2 causes vasodilatation of the coronary arterioles

Metabolic hyperaemia matches flow to demand
Adenosine (from ATP) is a potent vasodilator

Question 5

What extrinsic mechanisms control coronory blood flow?

Answer 5

Coronary arterioles supplied by sympathetic vasoconstrictor nerves BUT
Over-ridden by metabolic hyperaemia as a result of increased heart rate and stroke volume
So sympathetic stimulation of the heart results in coronary vasodilatation despite direct vasoconstrictor effect (functional sympatholysis)
Circulating adrenaline activates beta-2 adrenergic receptors, which cause vasodilatation

Question 6

When does peak left coronary flow occur?

Answer 6

during systole

Question 7

Which matter, grey or white, is very sensitive to hypoxia?

Answer 7

grey

Question 8

Which arteries anastomose to form CIRCLE OF WILLIS?

Answer 8

basilar (formed by the two verterbral arteries) and carotid

Question 9

Will cerebral perfusion be maintained if one carotid artery is obstructed?

Answer 9

Yes

Question 10

Is pulmonary capillary pressure high or low compared to systemic pressure?

Answer 10

low

Question 11

What does hypoxia do to pulmonary arterioles?

Answer 11

constricts (complete opposite affect in systemic arterioles)