Question

Calcium plays a very important role in the formation of bones,write on the role of endocrine glands and hormones responsible for maintaining Calcium Homeostasis.

Answer 1

Calcium homeostasis refers to the regulation of the concentration of calcium ions in the extracellular fluid [Ca⁺⁺]_ECF. This parameter is tightly controlled because the calcium ions have a stabilizing effect on voltage-gated ion channels. For instance, when [Ca⁺⁺]_ECF is too low (hypocalcemia), voltage-gated ion channels start opening spontaneously, causing nerve and muscle cells to become hyperactive. The syndrome of involuntary muscle spasms due to low [Ca⁺⁺]_ECF is called hypocalcemic tetany. Conversely, when [Ca⁺⁺]_ECF is too high (hypercalcemia), voltage-gated ion channels don't open as easily, and there is depressed nervous system function.

The two most important hormones for maintaining calcium levels in the body are parathyroid hormone (PTH) and 1,25(OH)₂D (the active form of vitamin D). The major regulator is PTH, which is part of a negative feedback loop to maintain [Ca⁺⁺]_ECF.