What is the cause of a myocardial infarction? a. Decreased ...

[vinney12]

What is the cause of a myocardial infarction?
 
  a. Decreased perfusion to the pulmonary ar-tery
  b. Partial or complete obstruction of a coro-nary artery
  c. Blockage in one or more of the great ves-sels
  d. Narrowing of part of the aorta

Question 2

The dicrotic notch recorded in the aorta immediately follows what mechanical event of the car-diac cycle?
 
  a. Closure of the aortic valve
  b. Closure of the atrioventricular valves
  c. Isovolume contraction
  d. Opening of the aortic valve

[katara]

Answer to Question 1

ANS: B
Partial obstruction of a coronary artery may lead to tissue ischemia (decreased O2 supply), a clin-ical condition called angina pectoris. Complete obstruction may cause tissue death or infarct, a condition called myocardial infarction (MI).

Answer to Question 2

ANS: A
Rather than immediately dropping off, aortic and pulmonary pressures rise again after the semi-lunar valves close. Note the feature termed the dicrotic notch, which is caused by the elastic re-coil of the arteries. This recoil provides the extra push that helps maintain the head of pressure created by the ventricles.

[vinney12]

Thanks for the timely response, appreciate it

[xiaomengxian]

Wow, this really help