NEET BIOLOGY

Detailed explanation-1: -Vitamin D promotes intestinal calcium absorption and helps maintain adequate blood levels of calcium and phosphorus, which is necessary for healthy bone mineralization. Vitamin D deficiency in children can cause rickets, leading to a bowlegged appearance due to the softening of the bones.

Detailed explanation-2: -1, 25(OH)2D increases calcium absorption by binding to the vitamin D receptor in the intestine (3). Optimal calcium intake is essential for mineralization of bone and plays a role in the prevention of osteoporosis and fractures among the elderly population.

Detailed explanation-3: -Vitamin D is probably absorbed through passive diffusion and a mechanism involving membrane carriers, especially cholesterol transporters, although data remain scarce. Some data suggest that fat, when consumed concomitantly with vitamin D, improves vitamin D absorption.

Detailed explanation-4: -Vitamin D promotes calcium absorption in the gut and maintains adequate serum calcium and phosphate concentrations to enable normal bone mineralization and to prevent hypocalcemic tetany (involuntary contraction of muscles, leading to cramps and spasms).

Detailed explanation-5: -While vitamin D has multiple effects on bone and calcium metabolism, the regulation of intestinal calcium (Ca) absorption efficiency is a critical function for vitamin D. This is necessary for optimal bone mineralization during growth, the protection of bone in adults, and the prevention of osteoporosis.