Coronary Circulation

Question 1

The left coronary artery supplies which parts of the coronary system?

Select all that apply

A. The sinoatrial node
B. The anterior wall of the left ventricle
C. The inferior wall of the left ventricle
D. The acute marginal coronary artery
E. The circumflex coronary artery

Answer 1

B & E

The anterior wall of the left ventricle and the circumflex coronary artery are supplied by the left coronary artery.

The sinoatrial node, the inferior wall of the left ventricle and the acute marginal coronary artery, as well as the right ventricle and most of the inter-ventricular septum, are supplied by the right coronary artery.

Question 2

Regarding venous coronary blood (true or false):

It is highly oxygenated compared to other venous blood in the body

Answer 2

False. Coronary venous blood flow is relatively deoxygenated because oxygen extraction in the myocardium is relatively high.

Question 3

Regarding venous coronary blood (true or false):

It drains mainly directly into the left ventricle

Answer 3

False. Coronary venous blood drains mainly into the right atrium.

Question 4

Regarding venous coronary blood (true or false):

It can contribute to physiological shunt

Answer 4

True. Some blood is drained into the left ventricle and, because of venous admixture, this may contribute to physiological shunt.

Question 5

Regarding venous coronary blood (true or false):

It flows into the coronary sinus

Answer 5

True. Coronary venous blood flow drains mainly into the right atrium via the coronary sinus and anterior coronary veins.

Question 6

Regarding venous coronary blood (true or false):

Its flow may be increased in pulmonary hypertension

Answer 6

True. Coronary venous blood flow may be increased due to collateral formation if pulmonary hypertension is present, leading to increased coronary sinus size.

Question 7

Regarding the body at rest (true or false):

The oxygen consumption of myocardium is around 2-4 ml/100 g

Answer 7

False. The oxygen consumption of myocardium is around 8-10 ml/100 g.

Question 8

Regarding the body at rest (true or false):

Oxygen extraction is around 90%

Answer 8

False. Oxygen extraction at around 60% is close to maximum, even at rest.

Question 9

Regarding the body at rest (true or false):

Myocardial perfusion is dependent on diastolic flow

Answer 9

True

Question 10

Regarding the body at rest (true or false):

Blood flow in coronary arteries depends on the pressure difference between aortic pressure and extravascular myocardial pressure

Answer 10

True

Question 11

Regarding the body at rest (true or false):

Lactic acid is produced by myocardial cells

Answer 11

False. Lactate production is a feature of metabolism during exercise, when oxygen requirements exceed oxygen delivery.

Question 12

Which of these substances leads to an increased release of NO in the intact coronary vascular endothelium?

Select all those that apply

A. Dopamine
B. Acetylcholine
C. Hyperoxia
D. Noradrenaline
E. Adenosine

Answer 12

B & E

Acetylcholine leads to NO release and vasodilatation. Adenosine leads to increased release of NO in the intact coronary vascular endothelium and therefore vasodilatation.

A. Incorrect. Dopamine is associated with NO inhibition and vasoconstriction.

C. Incorrect. Hypoxia, not hyperoxia, leads to NO release and vasodilatation.

D. Incorrect. Noradrenaline is associated with NO inhibition and vasoconstriction.