Cardiovascular

Cardiovascular generally pertains to the heart and blood vessels. A cardiovascular system which is also called the blood-vascular or the circulatory system is composed of the heart which is a muscular pumping device, and a close system of blood vessels or vasculature, veins, and capillaries.

Some characteristics of the cardiovascular system make it a unique and complex hydraulic system, such a fact is that it is a closed circle, and that it is elastic and  is filled with liquid at a positive mean pressure ("mean cardiovascular pressure"), which exists independent from the pumping action of the heart. The heart passively fills, rather than actively sucking, and the flow from it is periodic, while the flow to it is continuous.

The primary functions of the system are to maintain metabolic equilibrium as well as a favorable cellular surrounding. These functions though depend on the continuous and controlled flowing of blood through the thousands of miles of capillaries that reach the body’s every cell. Blood performs its ultimate transporting function (of which is the purpose of circulation) with the help of these microscopic capillaries: oxygen and nutrients pass from capillary blood into fluids surrounding the cells and waste products are also removed in the same manner, being taken into the capillary blood flow.

Another important function of the cardiovascular system is the protection of the body by white blood cells, antibodies, and complement proteins that circulate in the blood and defending the body against foreign microbes and toxins. Clotting mechanisms are also present and protect the body from losing blood after injuries.

Regulating the body temperature, fluid pH, and water content of cells is another purpose of the cardiovascular system.