Calcium, a white silvery soft alkaline metal, forms about 3% of the earth’s crust and is placed 22nd in the periodic table, after magnesium. Rarely found in its raw form, it is often sequestered or locked in limestone, fluorite and gypsum. It is abundantly found in stalactites and stalagmites as calcium carbonate.
Mildly soluble in water, calcium in water will transform to calcium hydroxide and release hydrogen gas seen as little bubbles on the surface of the metal. Calcium dissolves more readily in hydrochloric acid, releasing hydrogen gas and calcium ions in the aqueous state.
Though not needed in huge amounts, calcium is essential in making soil fertile, improve soil structure and improve micro-nutrients availability and improve the environment for micro-organisms . It reduces the acidity of soil and increases the PH level. It has been observed that area where lambsquarters, a calcium rich plant, thrive are often fertile farming land as well.
Calcium plays an essential role in plant and animal life. In plants, calcium and magnesium plays a major role in “gluing” the adjacent plant cells together, providing its skeletal structure. In animals, calcium constitutes 1.5% of the body weight. A 62kg person will have about 890g of calcium in his body.
Dissolved calcium is taken up by plants from the soil as calcium cathions. Calcium cations enters the root system of the plants through osmosis and travels to the leaves where it stays put until the plant sheds its leaves. In other words, calcium cations is phloem immobile. In trees, the calcium is deposited on the trunks until they return to the ground where it returns to the soil.
Calcium is needed in the healthy growth of human body. Calcium sequestered in calcium rich food is broken free during the digestion process by the stomach’s hydrochloric acid and absorbed in the duodenum ( first portion of the small intestine ). Calcium absorption reduces as it travels down the digestive tract as the medium gets more alkaline. The body keeps itself in equilibrium, as excess calcium is excreted by the body.
A diet high in protein, fatty diet or a huge intake of phytic acid ( as in oatmeal ) or certain vegetables rich in oxalate, example spinach, prevents proper absorption of calcium into the body. Mental stress, menopause and old age also retards calcium absorption into the body. . Calcium absorption is accelerated in times of bodily need as in growing children, lactating mothers and small dietary intake.
Vitamin D, synthesized by the body upon exposure in sunlight, is essential for the assimilation of calcium into the body. Impact exercise is also essential to sustain skeletal growth, which explains why space workers faces bone degeneration due to lack of skeletal impact in weightless space.