One of the 12 organ systems that can be examined. Which system includes the heart and blood vessels?

• A. Endocrine
• B. Cardiovascular
• C. Immune
• D. Reproductive

Answer: (B)

This item tests recognizing the cardiovascular system. The heart and blood vessels are the core components of this system, whose job is to circulate blood throughout the body. The heart acts as the muscular pump that pushes blood into the arteries, which branch into smaller vessels and return through veins, with capillaries enabling exchange of oxygen, nutrients, and wastes at the tissue level. This circulation supports tissue perfusion and helps regulate blood pressure. The other options describe different systems: the endocrine system uses glands and hormones to regulate processes; the immune system defends against pathogens; the reproductive system handles offspring production. So the system that includes the heart and blood vessels is the cardiovascular system.