Which component is NOT part of the circulatory system?

The lungs are primarily part of the respiratory system, which is responsible for the exchange of gases in the body. While they play a crucial role in facilitating oxygen intake and carbon dioxide removal, they do not form an integral part of the circulatory system itself. The circulatory system, also known as the cardiovascular system, is composed of the heart, blood vessels, and blood, all of which work together to transport oxygen, nutrients, hormones, and waste products throughout the body.

The heart acts as the pump that circulates blood, and blood vessels (arteries, veins, and capillaries) serve as the pathways for blood flow. Blood carries essential components needed for the body to function properly. The lungs, while interconnected with the circulatory system through the exchange of gases, are not classified as a component of that system. Thus, identifying the lungs as not being a component of the circulatory system is accurate.