Which statement best defines the cardiovascular system?

• A. It only pumps blood to the lungs.
• B. It is another name for the nervous system.
• C. It regulates body temperature through skin alone.
• D. It includes the heart and blood vessels and circulates blood throughout the body.

Answer: (D)

The cardiovascular system is made up of the heart and blood vessels that circulate blood throughout the body. The heart acts as the pump, sending oxygen-rich blood to tissues via arteries and returning oxygen-poor blood through veins, with blood traveling to the lungs for gas exchange and then to the rest of the body (pulmonary and systemic circulation). This system enables oxygen, nutrients, and waste removal to reach and be removed from every cell. It’s not just about the lungs, it’s not the nervous system, and it isn’t regulated by the skin alone. Therefore, the statement that best defines it is that it includes the heart and blood vessels and circulates blood throughout the body.