Which body system includes the heart and blood vessels?

• A. Respiratory system
• B. Cardiovascular system
• C. Nervous system
• D. Lymphatic system

Answer: (B)

The cardiovascular system, also called the circulatory system, includes the heart and the network of blood vessels. The heart acts as a muscular pump that pushes blood through arteries, veins, and capillaries, delivering oxygen and nutrients to tissues and returning waste products to be removed. The vessels form the continuous pathways that keep blood circulating throughout the body.

This system is distinct from the respiratory system, which handles breathing and gas exchange in the lungs; the nervous system, which controls body functions via the brain and nerves; and the lymphatic system, which manages immune defense and fluid drainage. So the heart and blood vessels together define the cardiovascular system.