Which organ system is described as comprising the heart and blood vessels?

• A. Nervous
• B. Pulmonary
• C. Endocrine
• D. Cardiovascular

Answer: (D)

The main concept here is the organization of circulation as a distinct network that includes the heart and the blood vessels. The heart serves as the muscular pump, while arteries, veins, and capillaries form the vast network that carries blood everywhere in the body. This arrangement enables oxygen and nutrient delivery to tissues and the removal of carbon dioxide and other wastes, sustaining perfusion and blood pressure. The other terms point to different bodily systems: the nervous system coordinates activities through nerves and the brain; the pulmonary/respiratory aspect relates to lungs and gas exchange; the endocrine system involves hormone-secreting glands. Only the cardiovascular description specifically covers both the heart and the vessels responsible for circulating blood.