Functions of Calcium in Body

Calcium (Ca) serves the following functions in body:

  1. Ca salts take part in bone and tooth development.

  2. The clotting of blood needs Ca ions.

  3. By regulating the membrane permeability, Ca ions control the excitability of nerves. If plasma ionized Ca level falls markedly, tetany results in which spasms of various muscle groups occur. Death may occur from convulsions of from laryngospasm. An excess of Plasma Ca depresses nervous activity.

  4. Ca ions acts as a cofactor or activator of certain enzymes, e.g. lipase, succinic dehydrogenase etc.

  5. Ca ions take part in the contraction muscles including heart muscles. With and increased plasma Ca, heart stops in systole (Ca rigor). In addition, a high plasma Ca decreases conductions of cardiac impulse and thus can cause heart block. Ca potentiates the effects of cardiac glycosides and therefore should not be given to patients who are using these drugs.

  6. Ca is essential for maintaining the integrity of capillary wall. In its deficiency, capillary walls become fragile and there is increased permeability of capillaries.

  7. Ca ions are involved in the release of catecholamines in the adrenal medulla in response to cholinergic stimulation.

   Toxicity if Calcium

An excessive intake of calcium can be dangerous because Ca gets deposited in various body tissues resulting in their malfunctioning.

   Calcium Excretion

Ca is excreted mainly in the feces (0.4 to 0.8 gram daily). The fecal Ca represents mostly the unabsorbed dietary calcium although some body Ca is also lost by this route. The urinary loss of Ca is 150 to 200 mg per day. Excessive sweating also results in an appreciable loss of body Ca.