Author Question: During the normal events of the cardiac cycle, which of the following statements is true? a. ... (Read 58 times)

urbanoutfitters · **on:** Jul 16, 2018

During the normal events of the cardiac cycle, which of the following statements is true?

a. Electrical depolarization follows mechan-ical contraction.
b. Electrical depolarization precedes me-chanical contraction.
c. Heart sounds precede electrical depolari-zation.
d. Heart sounds precede cardiac valve open-ing or closing.

Question 2

Significant loss of blood volume causes an increase in which of the following? 1. Vascular tone 2. Secretion of antidiuretic hormone (ADH) 3. Heart rate

a. 1, 2, and 3
b. 2 and 3 only
c. 1 and 3 only
d. 1 and 2 only

elizabethrperez · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: B
The P wave signals atrial depolarization. Within 0.1 sec, the atria contract, causing a slight rise in both atrial and ventricular pressures (the A waves).

Answer to Question 2

ANS: A
As the blood loss becomes more severe (20), atrial receptor activity decreases further. This in-creases the intensity of sympathetic discharge from the cardiovascular centers. Plasma ADH and heart rate continue to climb, as does peripheral vasculature tone.