by SMT

Created on: January 09, 2009   Last Updated: February 25, 2009

Hematology is the branch of physiology that addresses the study of blood. Blood is an essential component to human life that serves and carries out many vital bodily functions. Blood facilitates metabolic processes that encompass transportation of oxygen to other systems such as muscles, organs and the brain. Further it transports waste products like carbon dioxide and some toxins to be removed from the body through various mechanisms. Cells suspended in blood act as the first lines of defense against injury or infection by clotting mechanisms, and by transporting disease fighting cells like leukocytes (leuko means white, cyto means cell), and macrophages (macro means large, phage means eater) that clean up and digest debris and or harmful toxins and microorganisms. Lastly, the hematologic system maintains acid-base (pH) balances within the sensitive environment of the body.

Blood primarily consists of a fluid and a solid component that is made of formed elements. The combination of both fluid and formed element is termed blood volume. In an average adult, blood volume is equivalent to 6 quarts or in the metric system 5.5 liters of liquid. The fluid component of blood, called plasma, suspends and shuttles the solid, formed elements throughout the complex cardiovascular system. Plasma is approximately 90% water and the remaining 10% constitutes dissolved substances called solutes, which are made of organic and inorganic elements that contain electrolytes, proteins, gases, nutrients, waste products, and some hormones.

Electrolytes are essential in blood and important because they acts as an electric medium that can influence and regulate acid-base or pH functions. Electrolytes contain ionic compounds like sodium, potassium, calcium, magnesium, chlorine, phosphates, sulfates, and carbonic acids. These compounds ensure the body maintains appropriate balances of pH levels throughout many systems in the body in the form of buffers. The plasma also contains important proteins like albumin, globulins, fibrinogen, transferrin, and ferritin. The names are not as important, but understanding that these proteins main function is to provide osmotic pressure, act as buffers and binding agents, clotting factors and enzyme precursors is key.

Roughly 45-50% of blood volume is composed of formed elements, which are mostly cellular in nature and structure. There are three broad classifications of the types of cells that circulate throughout the vast network of blood vessels, capillaries,

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