Calcium is the fifth abundant element in the body which plays a vital role in skeletal structural units. The total calcium in the body is 100-170 gms, in which 99% present in the bones. The normal serum calcium levels are between 9-11 mg/dl. Values that are lower/higher than this will have its own consequences.
Factors that control the calcium homeostasis are parathyroid hormone, calcitonin by thyroid hormone, vitamin D and dietary intake of calcium and phosphate.
Roles of calcium in the body :
A large role in the formation of bones and teeth and maintance of skeletal structures :
The organic matrix of the bones and teeth are composed of calcium and phosphate in the larger amount. Hormonal imbalance like hypo/hyper secretion of thyroid, parathyroid, corticosteroids, and sunlight exposure will have a major effects on bone density and skeletal structures.
For membrane permeability :
Apart from sodium and potassium, ionised form of calcium in the extracellular fluid also have a role in membrane permeability, thus helps in balancing the inner and outer fluid content of the cells.
For normal heart rhythm :
Calcium ions are essential for the contraction of heart muscles thus help in maintaining the proper rhythmicity of the heart beat. Low blood calcium levels will increase the risk of ventricular tachycardia ( too rapid contraction of the lower chamber of the heart).
For neuromuscular excitability and muscle contraction :
Calcium ions are required for the electrical signalling process to generate impulse for neuromuscular excitability and muscle contraction. Low serum calcium level can cause hyper irritability and tetany ( muscle spasm) with characteristic carpopedal spasm, while the high concentration can cause depressed nerve conductivity and muscle rigor.
For coagulation of blood :
Calcium is one of the factor in the blood coagulation (blood clotting) cascade. Low blood calcium level will cause reduction in blood clotting ability and increased internal hemorrhage.
As secondary and tertiary messenger in hormone action :
Calcium acts as a messenger for the hormones to act on their target organs and to elicit desirable function. Low level of calcium will impair the adequate target – action ability.
Textbook of physiology by Guyton
Review of internal medicine by Harrisons
Textbook of oral pathology by Shafers.