Blood performs the following major functions.
- The plasma proteins maintain colloid osmotic pressure of the blood out of which 75% by albumins, 25% by globulins and almost none by fibrinogen.
- Transport of soluble organic compounds including nutrients, water, salts and waste products.
- All hormones are transported by blood from the endocrine tissues to the large cells.
- Transport of oxygen and carbon dioxide involves red blood cells.
- Defense against diseases. This is achieved in three ways.
a) Clotting of the blood by platelets and fibrinogen which prevents excessive blood loss and entry of pathogens.
b) Phagocytosis performed by the neutrophils, Monocytes and macrophages, which engulf and digest bacteria which find their way into the blood stream and body tissues.
c) Immunity achieved by antibodies and lymphocytes.
- Blood produces interferon and antitoxins, which are proteins and protect out body from nucleic acids of invading organisms, and toxins of the invaders.
- Maintenance of a constant blood solute potential and pH as a result of plasma protein activity. As the plasma protein and hemoglobin possess both acidic and basic amino acids, these can combine with or release hydrogen ions and so minimize pH change over a wide range pH values. In other words these act as a buffer.
- Distribution of excess of heat from the deeply seated organs. This helps to maintain a constant body temperature; blood also maintains concentration of water and salts; thus helps in homeostasis.
- Blood helps in exchange of materials between blood and body tissue through blood capillaries.
- Blood helps the body in maintaining the internal environment by producing heparin, histamines and also maintaining the amount of chemicals in the body to a constant or nearly constant level.
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