c) Describe the metabolic role of the phosphorous.
ANS-The metabolism of calcium and phosphorus is closely related and influenced by parathyroid hormone (PTH), vitamin D, and, to a lesser extent, calcitonin.
Calcium is absorbed in the proximal small intestine by active (transcellular) transport when intake is low and by diffusion when intake is high. Many factors influence absorption of calcium such as substances, which form insoluble complexes with calcium like phosphate. Phytates present in the husks of many cereals as well as in nuts, seeds, and legumes, can form insoluble calcium phytate salts in the gastrointestinal tract. Excess oxalates can precipitate calcium in the bowel. Human milk has a high calcium-phosphate ratio (2.2) as compared to cow's milk (0.77). Thus higher absorption of calcium is seen with human milk. Intestinal absorption of calcium is influences by Vitamin D.
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