A-2 Introduction to Veterinary Hematology
A.1 Function of Blood
Blood circulates in the body and acts as a transport medium that carries oxygen, essential nutrients, and
other materials to the cells of the body. It also serves to transport waste products for disposal. Neurons,
muscle cells, connective tissue cells, and epithelial cells draw their nourishment from interstitial
spaces, and respond to the glucose and oxygen content of that environment. Fresh supplies of oxygen
and glucose are exchanged with the blood circulating in the capillaries. Blood receives its oxygen from
the lungs and glucose from the intestines and liver.
Normal cell function depends on the rapid removal of toxic metabolic products (CO
2
and NH
3
) from
the interstitial fluid environment. These waste products are taken up by the plasma and red blood cells,
and eliminated as the blood passes through the kidneys and lungs. Blood also delivers hormones, lip-
ids, amino acids, salts, and vitamins, and removes urea and conjugated acids.
Blood distributes the heat generated by metabolizing body cells, so that body temperature is main-
tained at a constant level. In the event of vascular injury, blood platelets and plasma coagulation mech-
anisms prevent blood loss by aggregating with other platelets to form large hemostatic plugs (clots).
White blood cells protect against infections by identifying and killing invasive bacteria.
The number, size and distribution of blood cells provide important information for clinical diagnosis
and therapy.
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