Which of the following is used to describe the amount of blood ejected from the left ventricle during each contraction?

A. Respiratory bronchioles are part of the lower respiratory tract and lead to alveolar sacs, but they themselves are not primarily responsible for gas exchange. Their role is in the conduction of air.

B. Alveolar sacs are the primary site of gas exchange in the lungs. These sacs contain alveoli, where oxygen and carbon dioxide are exchanged between the air and the blood. This is the correct answer.

C. The pleura are double-layered membranes surrounding the lungs and do not play a direct role in gas exchange. They reduce friction and allow for smooth lung expansion.

D. Pulmonary veins carry oxygenated blood from the lungs back to the heart, but gas exchange occurs in the alveolar sacs, not the veins.

A. Angiotensin does not inhibit thirst; in fact, it stimulates thirst as part of its role in increasing blood pressure and fluid retention.

B. Angiotensin, specifically angiotensin II, stimulates vasoconstriction, which increases blood pressure by narrowing blood vessels. This is one of its primary actions in regulating blood volume and pressure.

C. Angiotensin actually promotes the retention of salt and water in the kidneys to increase blood volume and pressure, rather than stimulating their elimination.

D. Angiotensin does not inhibit antidiuretic hormone (ADH) release; it actually stimulates the release of ADH, which promotes water retention by the kidneys to increase blood volume.