What is the main function of the circulatory system?

The main function of the circulatory system is to transport nutrients and oxygen to cells throughout the body. It plays a crucial role in maintaining homeostasis and ensuring that tissues receive adequate supplies of oxygen and essential nutrients needed for energy production, growth, and repair. The circulatory system achieves this through a network of blood vessels that circulate blood, which carries oxygen from the lungs and nutrients from the digestive tract to every cell in the body.

Additionally, the system helps remove waste products, such as carbon dioxide and metabolic byproducts, from the tissues, which are then transported to excretory organs for elimination. This transport is vital for sustaining cellular functions and overall health. Other options, while important bodily functions, do not define the primary role of the circulatory system as accurately. For instance, digestion is primarily the function of the gastrointestinal system, protection against pathogens is a role of the immune system, and connecting the nervous system is not a direct function of circulation.