Calcium and Phosphate – Electrolyte Balance (Nursing)

by Jasmine Clark

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    00:00 So now let's look at the regulation of other electrolytes in the body including calcium and phosphate.

    00:08 99% of our body's calcium is going to be found in the form of calcium phosphate salts in our bones.

    00:17 Calcium balance is controlled by the parathyroid hormone and rarely deviates from normal limits.

    00:26 Parathyroid hormone is going to increase our calcium levels by targeting our bones by way of osteoclasts.

    00:34 Osteoclasts are going to break down our bones matrix and release the calcium and the phosphate from this breakdown to our blood.

    00:44 Calcium levels are also going to be regulated in the kidneys where we can get an increase in calcium reabsorption.

    00:52 This will lead to a decrease in phosphate ion reabsorption.

    00:58 Also in our small intestines, parathyroid hormone can also lead to an increase in our calcium absorption.

    01:06 And this is going to be indirectly through the stimulation of the kidneys to activate the vitamin D precursor, which then causes us to reabsorb or absorb more calcium in our GI tract.

    01:21 So 98% of our filtered calcium is going to be reabsorbed due to parathyroid hormone.

    01:29 If our extracellular fluid calcium levels are normal, then parathyroid hormone secretion is going to be inhibited.

    01:38 Also, 75% of our filtered phosphates are going to be reabsorbed in the proximal convoluted tubule of the nephron.

    01:47 Parathyroid hormone is going to inhibit this process.

    01:52 Phosphate reabsorption can also be affected by hormones such as insulin, which increases phosphate reabsorption, and glucagon, which are going to decrease phosphate reabsorption.

    02:07 So if we take a look at this or summarize this, starting with hypocalcemia, or low blood calcium levels, this is going to trigger a release of the parathyroid hormone from the parathyroid gland.

    02:24 Parathyroid hormone is then going to increase osteoclast activity in our bones, which is going to cause a breakdown of the bone matrix and a release of calcium and phosphate into the blood.

    02:39 Also, it will trigger the increase of calcium reabsorption and our kidneys tubules.

    02:46 And in the GI tract, first we're going to increase the activation of vitamin D.

    02:52 And then from there, vitamin D allows for increased calcium absorption in the small intestines.

    03:00 All of these effects will then lead to an increase or return to homeostatic calcium levels in the blood.

    About the Lecture

    The lecture Calcium and Phosphate – Electrolyte Balance (Nursing) by Jasmine Clark is from the course Fluid, Electrolyte, and Acid-base Balance – Physiology (Nursing).

    Included Quiz Questions

    1. Bones
    2. Thyroid
    3. Large intestines
    4. Small intestines
    5. Kidneys
    1. An increase in parathyroid hormone release
    2. An increase in osteoclast activity in bone
    3. An increase in calcium reabsorption in the kidney tubule
    4. An increase in vitamin D activation by the kidney
    5. A decrease in parathyroid hormone release

    Author of lecture Calcium and Phosphate – Electrolyte Balance (Nursing)

     Jasmine Clark

    Jasmine Clark

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