What is the primary function of the circulatory system?

The primary function of the circulatory system is to transport nutrients and gases throughout the body. This system comprises the heart, blood vessels, and blood, and it plays a crucial role in supplying oxygen from the lungs to the tissues and transporting carbon dioxide from the tissues back to the lungs for exhalation. Additionally, the circulatory system delivers essential nutrients absorbed from the digestive tract to cells, tissues, and organs, ensuring that they receive the necessary substances to function effectively.

Furthermore, the circulatory system also facilitates the movement of hormones from glands to their target organs and tissues, although hormone production itself is not a primary function. While the immune system offers defense against pathogens and the body has mechanisms for storing energy reserves, these processes are not the main activities performed by the circulatory system. Instead, its core purpose revolves around maintaining homeostasis via effective nutrient and gas transport, which is vital for sustaining life.