Question

which step occurs first in the vascular system?
o a. blood leaves the left side of the heart via the aorta.
o b. blood leaves the right side of the heart via the pulmonary artery.
o c. blood either leaves the aorta and goes to the upper body and head, or travels to the lower body.
o d. blood loses carbon dioxide, picks up oxygen in the lungs, and then returns to the hearts left side via the pulmonary vein.

Explanation:

In the vascular system, de - oxygenated blood first leaves the right side of the heart via the pulmonary artery to go to the lungs for oxygenation. Option a is part of the systemic circulation (oxygenated blood leaving the left side of the heart), but it occurs after the pulmonary circulation. Option c is also part of the systemic circulation. Option d is the return of oxygenated blood from the lungs to the heart (pulmonary vein), which occurs after blood has left the right side of the heart via the pulmonary artery.

Answer:

B. Blood leaves the right side of the heart via the pulmonary artery.