Human circulatory system has several key functions in our body, such as,

1. Transport of oxygen and nutrients – The blood takes oxygen from the lungs and delivers it to the rest of the body for their function.
2. Blood clotting – When we get a cut which causes bleeding our circulatory system helps to deliver blood platelets to the injury site to prevent excessive blood loss by forming a clot.
3. Regulation of body temperature – It transports heat from the core to the surface, enabling heat loss through the skin and maintaining a stable internal temperature.