Functions of the Vascular System

Abstract

General structure and function of the vascular system. The vessels - arteries, capillaries and veins - together with the heart constitute the cardiovascular system. This is a transport system, within which the medium to be transported (blood) is propelled by a pump (the heart) in a closed circuit through elastic tubes (vessels). This continual circulation of fluid throughout the body serves, most importantly, as a means of delivery and removal of substances; it provides all the living cells of the organism with the materials required for their normal functions (e.g., O2 and nutrients), and it carries away the products of cell metabolism (CO2 and other metabolites). These substances do not enter and leave the bloodstream directly; their passage is indirect, by way of the interstitial (extracellular) fluid. The many other functions of the circulatory system, discussed elsewhere in this book, are summarized on p. 402.