While at rest the whole body extracts approximately

7.
While at rest, the whole body extracts approximately 25% of the oxygen from its arterial
blood flow, and the myocardium extracts approximately what percentage?
a. 40%
b. 50%
c. 60%
d. 70%
ANS: D
Even at rest, the myocardium extracts approximately 70% of the oxygen from its arterial
blood flow, compared with a 25% extraction rate for the whole body.
DIF: Recall REF: 307
8.
Which of the following is the most important factor governing coronary blood flow?

DIF: Recall REF: 308
9.
During which part of the cardiac cycle does most coronary perfusion occur?
DIF: Recall REF: 308-309
10.
Which of the following statements are true of the sinoatrial node?
I. It is embedded in the right atrial muscle.
II. It is near the superior vena cava.
III. It initiates the electrical impulses that produce sequential atrial and ventricular contraction.
IV. It is near the right ventricle.
DIF: Recall REF: 309
11.
Which of the following is the main type of adrenergic receptor in the heart?
a.

b.

1
c.

2
d. Nicotinic
ANS: B
Sympathetic fibers are distributed throughout the entire heart. Cardiac sympathetic receptors
are mainly of the 
1
type.
DIF: Recall REF: 310
12.
Which of the following is the preferred biomarker for diagnosing acute myocardial infarction?

DIF: Recall REF: 313
13.
How soon do levels of troponins rise after a myocardial infarction?
DIF: Recall REF: 313