The Vascular System: Blood Flow Patterns in Various Parts of the Circulation

The patterns of blood flow vary throughout the vascular system. Firstly, the arteries have distensible walls which exhibit the familiar pulse, but also have characteristic flow patterns, including parabolic blood velocity profiles. Particular organs such as the brain, lungs, and the heart itself have special features associated with blood supply. Arterial disease is common in the developed world, and various drugs affect hemodynamics. The microcirculation (including capillaries) has special properties allowing exchange of metabolites between blood and surrounding tissue, and finally the veins have characteristics which complete the circuit. Cardiac output and venous return are balanced, and the factors affecting each are described, in particular, the way the balance point is altered by changes such as exercise or disease.