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Glossary

Starting with A for "ACE inhibitor" and continuing through to Y for "Yolk Sac Tumour", we give you succinct explanations for scientific and medical terms in clear and simple words.




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Calcium
Chemical element, symbol Ca. A soft silver-white and shining metal which is unstable in air and which reacts violently with oxygen and water. In man, calcium is predominantly stored in bone tissue. The calcium content is ca. 1.5% of body weight and is normally kept within narrow limits by the interactions between the hormones calcitriol, calcitonin and parathormone. In serum, calcium is present to about 55% as the functionally important ionised form, Ca++. About 40% is protein bound and about 5% bound to organic acids. If the blood is acidified as a result of disturbances in the body's acid-base balance and there is an excess of acid (acidosis), this leads to an increase in ionised calcium in the blood. Conversely, an excess of base (alkalosis) leads to a decrease in ionised calcium.

Functions
The important functions related to calcium include blood coagulation, the normal excitability of nerve and muscle tissue and the development of tension in muscles. Calcium also has supportive functions as a component of bones and teeth. Potassium, magnesium and phosphate ions partially oppose the actions of calcium.

Presence in food
Milk and milk products are foods which are particularly rich in calcium, but so are some types of vegetable, including broccoli, spinach and kale. The daily requirement for an adult is about 800-1000 mg.

Symptoms of deficiency
Muscular spasm, loss of calcium phosphate from the bones, osteoporosis as a result of dietary imbalance, disturbances in absorption when there is vitamin D deficiency or hormonal disturbance.

Clinical uses
Calcium salts in combination with other substances for osteoporosis.

Glossary entries:  Roche and Walter de Gruyter, Berlin