The human body requires calcium for normal function. Good sources of this mineral include dairy products, kale, almonds, oysters, spinach, navy beans and fortified cereal. The Food and Nutrition Board of the Institute of Medicine of the National Academies set the adequate intake of calcium at 1,000 mg per day for men and women aged 19 to 50.
Bone & Teeth Formation
The bones and teeth contain 99 percent of the calcium in the body, according to the Linus Pauling Institute at Oregon State University. This mineral provides structure for the bones and teeth in the form of hydroxyapatite, a salt made of calcium and phosphorus. Calcium also helps prevent osteoporosis, a weakening of the bones that increases the risk for fractures. As a result, men and women over the age of 50 have increased calcium needs. The Food and Nutrition Board recommends a daily intake of 1,200 mg for people in this age group, according to MedlinePlus.
Cofactor
Calcium acts as a cofactor for chemical reactions in the body. The City University of New York, Brooklyn defines a cofactor as a non-protein substance that speeds up chemical reactions. One of the most common uses of calcium as a cofactor involves coagulation of the blood. Calcium binds to clotting factors in the blood to produce clots and stop bleeding after a cut or other injury.
Blood Vessel Regulation
Calcium plays a role in blood vessel constriction and dilation, also known as vasoconstriction and vasodilation. Blood vessels constrict when calcium concentration in the intracellular fluid increases. The vessels dilate when intracellular calcium concentration decreases.
Hormone Secretion
Calcium affects the amount of hormone secreted by the parathyroid glands. When blood calcium levels fall below the normal range, the parathyroid gland secretes PTH to bring calcium levels back to normal. The normal amount of calcium in the blood ranges from 8.9 to 10.4 mg/dL, according to UT Southwestern Medical Center.
Muscle Contraction
Calcium allows the muscles to contract and relax properly. For muscle contraction to occur, muscle fibers must receive nerve impulses. These impulses stimulate muscle contraction, causing calcium ions to enter the muscle cells. These ions bond to proteins, which stimulates the release of calcium ions from storage units inside the muscle cell. When calcium binds with a protein known as calmodulin, enzymes break down a chain of glucose to provide energy for muscle contraction. Calcium binds with troponin-c to activate a series of reactions that cause muscle contraction.
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