Regulation of Calcium and Phosphate Balance

A normal blood Ca2+ concentration is critically important for contraction of muscles and maintenance of proper membrane permeability. Parathyroid hormone promotes an elevation in blood Ca2+ by stimulating resorption of the calcium phosphate crystals from bone and renal excretion of phosphate. A derivative of vitamin D produced in the body, 1,25-dihydroxyvitamin D3, promotes the intestinal absorption of calcium and phosphate.

The calcium and phosphate concentrations of plasma are affected by bone formation and resorption, intestinal absorption of Ca2+ and PO43-, and urinary excretion of these ions. These processes are regulated by parathyroid hormone, 1,25-dihydroxy vitamin D3, and calcitonin, as summarized in table 19.7.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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