biology

The Circulatory System Circulatory System is the combined function of the heart, blood, and blood vessels to transport oxygen and nutrients to organs and tissues throughout the body and carry away waste products. The circulatory system increases the flow of blood to meet increased energy demands during exercise and regulates body temperature. Also, when foreign substances or organisms invade the body, the circulatory system quickly sends disease-fighting elements of the immune system, such as white …

…phase between heartbeats. Blood pressure varies between individuals and even during the normal course of a day in response to emotion, exertion, sleep, and other physical and mental changes. The average normal blood pressure is about 120/80 mm Hg. Higher blood pressures that are sustained over a long period of time may indicate hypertension, a damaging circulatory condition. Lower blood pressu! res could signal shock from heart failure, dehydration, internal bleeding, or blood loss. ------------------------------------------------------------------------ **Bibliography**