Final answer:
Vitamin D (calcitriol) is required for the uptake of calcium from the gut. It plays a crucial role in the absorption of calcium and phosphorous from the small intestine, as well as the reabsorption of calcium in the kidneys. Vitamin D is essential for maintaining normal serum concentrations of calcium and phosphate.
Step-by-step explanation:
Vitamin D, specifically calcitriol, is required for the uptake of calcium from the gut. It plays a crucial role in the absorption of calcium and phosphorous from the small intestine, as well as the reabsorption of calcium in the kidneys. Vitamin D is essential for maintaining normal serum concentrations of calcium and phosphate, which are important for bone health, muscle contraction, hormone secretion, and neurotransmitter release.