Abstract
The main functions of the blood are the transport, and delivery of oxygen and nutrients, removal of carbon dioxide and waste products of metabolism, distribution of heat and signals of immune system. They are provided by circulation due to the driving force of the heart. Circulation of the blood depends on its rheological properties of the blood as well as on characteristics of the vessels through which the blood passes. The blood flow resistance is influenced by the complicated architecture of the vascular network and flow behaviour of blood components – blood cells and plasma. The obtained data based on analysis of influences on blood flow are differentiated in the dependence on place and level of investigation. At a macroscopic level the blood appears to be a liquid material, but at a microscopic level the blood appears to be a material with microscopic solid particles of varying size – various blood cells. From this point of view, we have to consider the blood flow in large vessels, and also on the level of microvessels. This division of facts of hemorheology is somewhat simplistic, but is very useful from the point of view of explanation and comprehension.