All about Calcium minerals -classification || Physiological functions || Calcium foods || Tablets || Supplements

MINERALS (Calcium)

Introduction : Our body contains 29 differents elements. Minerals constitute about 8% of body weight. These minerals are essential for a number of metabolic processes like blood coagulation, muscle contraction and enzyme action.

image : all about Calcium

Classification of mineral elements :

i) Principal elements (Macro minerals) - calcium, magnesium, sodium, potassium, phosphorous, sulphur and chlorine.

ii) Trace elements (Micro minerals ) -

1. Essential trace elements : iron, iodine, zinc, copper, cobalt and fluorine

2. Possibly essential trace elements : nickel, vanadium, tin and silicon

3. Non-essential trace elements : aluminum, cadmium, arsenic, lead and mercy

CALCIUM

 Of all the minerals, calcium is present in large amounts in the body. It constitutes 2% of body weight. A normal adult has 1200 grams of calcium in the body.

Physiological functions :

1. Calcium is necessary for the formation and growth of bones and teeth

2. It is essential for coagulation of blood

3. It is essential for transmission of nerve impulses

4. It is also necessary for muscle contraction

5. It helps in maintaining acid balance and water balance

6. It activates a number of enzymes

Sources : Milk, cheese and vegetables

Blood calcium : In blood, calcium is present only in the plasma. The plasma concentration of calcium is 9 to 11 mg %.

Plasma calcium exists in three forms -

1. Ionised or diffusible form

2. Unionised or non -diffusible form

3. Unionised complex with citrate

 Except unionised form, the other two forms can diffuse through cell membranes and capillaries.

Factors maintaining plasma calcium :   Maintenance of normal plasma calcium level is governed by the following factors -

1. Parathyroid hormone : It maintains plasma calcium by mobilising calcium from bones

2. Vitamin D : It increases the absorption of calcium from intestine

3. Plasma proteins : About 40% of plasma calcium is bound to plasma proteins (mainly albumin). A decrease in plasma proteins may decrease plasma calcium level

4. Plasma phosphate : Increase in plasma phosphate level produces a decrease in plasma calcium level. The reverse is also true. Thus there is an inverse relationship between plasma level of calcium and phosphate

5. Calcitonin : Increase in plasma calcium level stimulates the release of calcitonin. Calcitonin, in turn induces the deposition of calcium in the bone. Thus, calcitonin regulates plasma calcium level

Diseases related to calcium metabolism :

1. Tetany - It is a manifestation of hypocalcemia as occurs in hypoparathyroidism. There is increased neuro muscular excitability in tetany. This leads to -

• Fibrillation and twitching of muscles

• Muscular spasm

• Epilepsy like convulsions

2. Osteoporosis - It is a metabolic disorder. It occurs as a result of calcium deficiency. It also occurs in hypothyroidism and deficiency of vitamin D. In osteoporosis, calcification of bones is defective. Bones become spongy and brittle. So spontaneous fracture of bones is very common. It is treated by calcium supplemented diet and vitamin D

3. Rickets - It occur in children due to the deficiency of calcium. Also it occurs in deficiency of vitamin D

Features :

• Softness and deformities of bones (like bow -legs and pigeon chest)

• Delay in closure of fontenelle

• Delay in tooth formation

4. Osteomalacia - It is a calcium deficiency disease which occurs in adults. Also, it occurs due to deficiency of vitamin D

Features :

• Deformities and easy fracture of bones

• Bending of vertebrae and bow -legs

• Muscle weakness and pain