Final answer:
Active vitamin D, known as calcitriol, is integral in regulating calcium concentration by enhancing absorption from the digestive tract, promoting reabsorption in the kidneys, and influencing bone calcium release through the activity of parathyroid hormone. It is essential for bone health, muscle function, and numerous cellular processes, and is more akin to a hormone than a vitamin.
Step-by-step explanation:
How Active Vitamin D Regulates Calcium Concentration
Active vitamin D, known as calcitriol (1,25-dihydroxycholecalciferol), regulates calcium concentration in several key ways. First, it enhances the absorption of calcium from the digestive tract, which is crucial for maintaining normal serum levels of calcium and phosphate, necessary for overall health, including bone health and muscle function. In addition, active vitamin D facilitates calcium reabsorption in the kidneys, ensuring that the body retains this vital mineral. It also modulates the intake of calcium by influencing the activity of the parathyroid hormone (PTH), which in turn regulates bone calcium release and decreases the pH in the intestines to promote calcium absorption.
Moreover, deficiency in active vitamin D can lead to skeletal disorders such as osteoporosis and rickets, as well as impair cellular processes, neuromuscular functions, blood clotting, and the inflammatory response. It's important to note that vitamin D is not just a vitamin but acts more like a hormone due to its wide-reaching effects and presence of receptors in many types of cells across the body. Therefore, the active form of vitamin D, dihydroxyvitamin D, is an essential component required by the body for the absorption of calcium, highlighting its systemic importance.