The primary role of each heartbeat is to:

The primary role of each heartbeat is to:

• A. Move blood through the veins only
• B. Eject blood at sufficient pressure to supply tissues and remove wastes
• C. Pump blood only to the lungs
• D. Cause vasodilation to regulate pressure

Answer: (B)

The heartbeat’s main job is to propel blood with enough force to keep tissues perfused and to carry away wastes. When the heart contracts, it ejects blood into the arteries, creating pressure that drives flow through both the pulmonary circuit (to the lungs) and the systemic circuit (to the rest of the body). This perfusion supplies oxygen and nutrients to cells and removes carbon dioxide and other wastes. The lungs aren’t the heart’s only destination for blood—the left ventricle sends blood to the entire body, while the right ventricle sends blood to the lungs. Regulation of vessel diameter and blood pressure is handled mainly by the vessels and autonomic controls, not by the heart’s primary pumping action. So the key idea is that each heartbeat serves to generate enough pressure to circulate blood and sustain tissue perfusion and waste removal.

The heartbeat’s main job is to propel blood with enough force to keep tissues perfused and to carry away wastes. When the heart contracts, it ejects blood into the arteries, creating pressure that drives flow through both the pulmonary circuit (to the lungs) and the systemic circuit (to the rest of the body). This perfusion supplies oxygen and nutrients to cells and removes carbon dioxide and other wastes. The lungs aren’t the heart’s only destination for blood—the left ventricle sends blood to the entire body, while the right ventricle sends blood to the lungs. Regulation of vessel diameter and blood pressure is handled mainly by the vessels and autonomic controls, not by the heart’s primary pumping action. So the key idea is that each heartbeat serves to generate enough pressure to circulate blood and sustain tissue perfusion and waste removal.