Regulating Blood Calcium Levels

To inhibit osteoclast activity, stimulate the kidneys to increase calcium loss in the urine, and reduce blood calcium levels.

During periods of high bone turnover, such as in growing children.

Temporary decrease in blood calcium levels.

<p>Calcitonin stimulates the kidneys to increase calcium loss in the urine.</p> Signup and view all the answers

<p>PTH and calcitriol increase blood calcium levels, while calcitonin reduces blood calcium levels.</p> Signup and view all the answers

<p>The thyroid gland, specifically the parafollicular cells.</p> Signup and view all the answers

<p>The normal range of calcium concentration in the blood is between 8.9 and 10.1 milligrams per deciliter (mg/dL). Calcium is required for numerous physiologic processes such as muscle contraction, exocytosis of molecules from cells, stimulation of the heart by pacemaker cells, and blood clotting.</p> Signup and view all the answers

<p>High blood calcium levels and stress from exercise.</p> Signup and view all the answers

<p>The two primary hormones that regulate blood calcium levels are calcitriol (an active form of vitamin D) and parathyroid hormone.</p> Signup and view all the answers

<p>Calcitonin inhibits osteoclast activity, reducing bone resorption and calcium release into the blood.</p> Signup and view all the answers

<p>The precursor molecule is 7-dehydrocholesterol, a modified cholesterol molecule.</p> Signup and view all the answers

<p>Parathyroid hormone increases the final enzymatic step of converting calcidiol to calcitriol in the kidney.</p> Signup and view all the answers

<p>PTH and calcitriol act synergistically to increase the release of calcium from the bone into the blood by increasing osteoclast activity.</p> Signup and view all the answers

<p>Vitamin D3 is converted by liver enzymes to calcidiol by the addition of a hydroxyl group (—OH).</p> Signup and view all the answers

<p>The active form of vitamin D3 is calcitriol, which is formed by the addition of another —OH group to calcidiol in the kidneys.</p> Signup and view all the answers

<p>PTH and calcitriol act synergistically to stimulate the kidneys to excrete less calcium in the urine and retain more calcium in the blood.</p> Signup and view all the answers

<p>Calcitriol increases the absorption of calcium ions from the small intestine into the blood.</p> Signup and view all the answers

<p>The presence of parathyroid hormone increases the rate of the final enzymatic step in the kidney, where calcidiol is converted to calcitriol.</p> Signup and view all the answers

<p>Regulating blood calcium levels is essential because calcium is required for numerous physiologic processes such as muscle contraction, exocytosis of molecules from cells, stimulation of the heart by pacemaker cells, and blood clotting.</p> Signup and view all the answers

<p>A low blood calcium level is the initial stimulus for the parathyroid glands to release parathyroid hormone.</p> Signup and view all the answers

<p>The skeleton plays a role in the storage of calcium, which is why blood calcium regulation is discussed in the context of the skeletal system.</p> Signup and view all the answers

<p>Rickets is characterized by overproduction and deficient calcification of osteoid tissue, leading to a bowlegged appearance.</p> Signup and view all the answers

<p>The net effect of calcitriol on bone is dependent on blood calcium levels.</p> Signup and view all the answers

<p>PTH and calcitriol act synergistically to stimulate the kidneys to excrete less calcium in the urine and retain more calcium in the blood.</p> Signup and view all the answers

<p>The result is an elevation of blood calcium levels and return to within the normal homeostatic range.</p> Signup and view all the answers

<p>The release of additional PTH is inhibited by negative feedback.</p> Signup and view all the answers