ABSTRACT
Blood is a “§uid tissue” of nonhomogeneous composition; blood cells are suspended in protein-enriched plasma that circulates throughout the body via a complex network of vessels. The volume fraction of red blood cells (RBCs) in blood is known as the hematocrit. Because RBCs are directly responsible for oxygen delivery and gas exchange, hematocrit and the blood §ow rate directly impact ef¦ciency of gas exchange. The cellular component of blood also includes leukocytes (white blood cells), which play an important role in the immune response. In general, the viscosity of blood is dependent on the cellular concentration and will consequently affect the nature of blood §ow, including §ow rate, §ow pro¦le, etc. Certain pathological conditions, such as sickle cell anemia, in which RBC abnormalities cause cell stiffening and clumping, exhibit higher effective blood viscosity and subsequently altered §ow.
