What components make up the cardiovascular system?

The cardiovascular system is fundamentally composed of the heart, blood, and blood vessels. The heart serves as the central pump that circulates blood throughout the body, delivering oxygen and nutrients to tissues while removing waste products. Blood, the fluid medium, transports these essential substances and also plays a critical role in immune responses and temperature regulation. Blood vessels, including arteries, veins, and capillaries, form a complex network that facilitates the movement of blood to and from all areas of the body.

The other options mention components that are not part of the cardiovascular system. Nerves and muscles play important roles in the regulation and functioning of the cardiovascular system, but they are not structural components of it. The lungs, while essential for gas exchange, are part of the respiratory system, not the cardiovascular system. Similarly, organs like the stomach, liver, and kidneys are part of the digestive and excretory systems, which, although they interact with the cardiovascular system, are not integral components of it. Thus, the selection of the heart, blood, and blood vessels accurately identifies the core components of the cardiovascular system.