Vitamin D: Introduction

by Kevin Ahern, PhD

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    Vitamin D is the other fat-soluble vitamin I want to talk about here. Now, vitamin D is important in a variety of functions in the body. One of the things that we know about for it best is it regulates the intestinal absorption of calcium, iron, magnesium, phosphate, and zinc. We’re going to focus on calcium here. Vitamin D is not exactly a vitamin. Technically, vitamins are something that we can’t make, but we actually make most of the vitamin D that we need. Vitamin D therefore acts more like a hormone then it does like a vitamin, but nonetheless the name persists. Vitamin D is ultimately derived from cholesterol or by supplements that we take. And people who don’t get enough sunlight for example or live in areas where there’s limited sunlight may need supplements to get the full amount of vitamin D that they need for their bodies. Cholecalciferol is a form of vitamin D known as D3, that’s created by exposure to sunlight. And that form of vitamin D3 is also the form that we take when we take oral forms of vitamin D as supplements. The formation of cholecalciferol or vitamin D can happen as a result of reaction that you see in the slide on the right. In this reaction, 7-dehydrocholesterol is converted to cholecalciferol simply by the presence of UV light. So if you get enough UV light and you have a light enough skin, getting sufficient vitamin D isn’t a problem. However, if you don’t get enough exposure to UV light or you’re in an area where you have dark skin and the light levels are low, you may be deficient in the vitamin D. Now, cholecalciferol or vitamin D3 is not the active form of vitamin D. It can be converted into...

    About the Lecture

    The lecture Vitamin D: Introduction by Kevin Ahern, PhD is from the course Vitamins. It contains the following chapters:

    • Vitamin D
    • Vitamin D3 Forms

    Included Quiz Questions

    1. It has its active form carefully regulated in the body.
    2. It is created by exposure of cholesterol to light.
    3. It results in scurvy, if deficient.
    4. All of the answers are true.
    5. None of the answers are true.
    1. It is hydroxylated in the liver to calcifediol.
    2. It is hydroxylated in the liver to calcitriol.
    3. It is a precursor of ergocalciferol.
    4. All of the answers are true.
    5. None of the answers are true.

    Author of lecture Vitamin D: Introduction

     Kevin Ahern, PhD

    Kevin Ahern, PhD

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