Control and Regulation of Calcium and Phosphorus

by Thad Wilson, PhD

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    These hormones that control calcium and phosphorus or phosphate are parathyroid hormone. And where does parathyroid hormone come from? The thyroid gland has four nodules in it, and these are parathyroid nodules. These parathyroid hormones are going to do a few functions for us. The first thing it does is it acts to reabsorb calcium, to not reabsorb phosphate, and to activate vitamin D. So vitamin D has a few forms converted to its most active form of vitamin D, which is known as D3. D3 is going to have hormonal actions on its own. But let’s put that aside just for a second and talk about what parathyroid hormone is doing. Since it is reabsorbing more calcium from the kidney, you’re going to be able to be putting more calcium back into the circulation. It is dumping phosphate or not reabsorbing it, so you are losing some phosphate. Parathyroid hormone also acts on the bone to cause calcium to be reabsorbed. So this is working on your stores of calcium in the body, breaking them down, for what purpose? So you’re reabsorbing it from your kidney, you’re reabsorbing it from the bone. Why are you doing all this work? The big issue is you need to maintain plasma calcium levels somewhere in between about 8.5 to 10.6 milligrams per deciliter. How do you do that? You are reabsorbing bone from these two locales and moving it into the plasma. This movement of calcium from its stores in the bone and when it’s being reabsorbed increase plasma calcium levels. If you increase plasma calcium levels enough, you can decrease parathyroid hormone. So, really, parathyroid hormone is stealing calcium from the bone by having to undergo reabsorption. You might ask, well, I really thought we wanted to save our calcium? We...

    About the Lecture

    The lecture Control and Regulation of Calcium and Phosphorus by Thad Wilson, PhD is from the course Musculoskeletal Physiology.

    Included Quiz Questions

    1. 1,25-(OH)2-Vitamin D
    2. Thyroid hormone
    3. Parathyroid hormone
    4. Cortisol

    Author of lecture Control and Regulation of Calcium and Phosphorus

     Thad Wilson, PhD

    Thad Wilson, PhD

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