Chemistry

The Chemistry of Calcium and its Relation to Biological Function



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In the 1980s, the dairy industry in the US pushed the importance of dairy with the advertising slogan: "milk, it does a body good." Typically, when the average person thinks of why milk is good for the body, they think of the fact that it is a good source of calcium. On a very basic level, calcium is important for strong, healthy teeth and bones. But when one gets down to a molecular level and begins to look at the chemistry behind this important element and its relation to biological functions, it goes well beyond maintaining the health of teeth and bones.

Calcium is the most abundant mineral in the human body. The average adult has just over two pounds of it in their body (1 kilogram). Ninety-nine percent of this is in the bones as calcium phosphate salts. The extracellular fluid also contains calcium, and there is an exchange of the mineral between the skeleton and the extracellular fluid everyday. Calcium ranges in the serum of the extracellular fluid are highly regulated by the body, and it varies in relation to the amount of albumin in the serum, a protein to which calcium binds.

Calcium is taken in through the diet, and vitamin D is needed for absorption into the intestines. Calcium is excreted and lost from the body in urine and feces, but most is retained in the bones, which are the primary storage area of calcium in the body. Calcitonin is a chemical that stimulates the incorporation of calcium into bones. In contrast, parathyroid hormone releases calcium from bones.

The levels of calcium in the body are regulated by calcitonin, parathyroid hormone, and vitamin D. The regulatory organ behind this is the parathyroid gland, which is located behind the thyroid gland in the neck. When calcium levels in the body are low, this gland releases parathyroid hormone to release the element from the bones. The thyroid produces calcitonin in response to high levels of calcium in the blood, but parathyroid hormone is more significant.
Calcium ions are a widespread second messenger in signal transduction. Calcium-selective ion channels in the neurons are important to synaptic functions in the brain. If calcium ions enter cells in excessive amounts, they can cause damage to the cells or even cell death. When the ions enter the plasma membranes of a cell, they cause a specific action depending on the type of cell. The mineral's role in muscle contraction has been known for over a century, and calcium ions are stored in the sarcoplasmic reticulum of muscle cells.

In other organisms, such as invertebrates, calcium plays a role in building exoskeletons (such as shells) and endoskeletons (such as those found in echinoderms). Calcium ions are also an important component of the cell walls and cell membranes found in plants. In addition, they help keep a balance in plant cell vacuoles. This is done by a counter action of the positive calcium ions versus organic anions (negative ions) in the vacuole.

A lack of calcium in the body can lead to debilitating effects, such as osteoporosis, decrease in brain function, and decrease in muscle contraction. It goes beyond just strong bones and teeth. So make sure that if you aren't getting enough in your diet that you obtain the recommended daily allowance through supplements. Although be careful in your dosage too much calcium, like anything else can be damaging to the body. As always, consult a physician to make sure you are treating your body properly.

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