Vitamins 1
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Questions and Answers

What is the primary reason why vitamins are essential for the human body?

  • Because they can be synthesized in the body in sufficient quantities
  • Because they are a major component of body tissue structure
  • Because they are catalysts that provide energy to the body
  • Because they are essential for health and growth (correct)

    • What is a characteristic of vitamins in the human body?

  • They are oxidized to give energy to the body
  • They are synthesized in the body in sufficient quantities
  • They do not enter into the body's tissue structure (correct)
  • They are needed in large amounts to maintain health

    • Why must vitamins be taken in through food?

  • Because they provide energy to the body
  • Because they are not essential for health and growth
  • Because the body cannot synthesize them in sufficient quantities (correct)
  • Because they are a type of macronutrient

    • What is the process by which vitamin A is transported to the liver?

    <p>Through chylomicrons</p> Signup and view all the answers

    What role do vitamins play in the body?

    <p>They act as catalysts to facilitate bodily functions</p> Signup and view all the answers

    What is the function of rhodopsin in the retina?

    <p>To transmit light signals to the brain</p> Signup and view all the answers

    What is a common characteristic of all vitamins?

    <p>They are organic substances needed in small amounts</p> Signup and view all the answers

    What is the form of vitamin A that is essential for visual function?

    <p>Retinol</p> Signup and view all the answers

    What is a consequence of not consuming enough vitamins?

    <p>Deficiency diseases may occur</p> Signup and view all the answers

    What is the result of vitamin A deficiency in the retina?

    <p>Night blindness</p> Signup and view all the answers

    What is a primary function of vitamins in the body?

    <p>To act as catalysts to facilitate bodily functions</p> Signup and view all the answers

    What is the role of retinol-binding protein in vitamin A metabolism?

    <p>To transport vitamin A in the blood</p> Signup and view all the answers

    What is the function of vitamin A in bone growth and development?

    <p>To facilitate bone calcification</p> Signup and view all the answers

    Why are vitamins considered essential nutrients?

    <p>Because they are essential for health and growth</p> Signup and view all the answers

    What is the precursor to vitamin A that is converted to retinol?

    <p>Carotene</p> Signup and view all the answers

    What is the name of the pigment found in the rods of the retina?

    <p>Rhodopsin</p> Signup and view all the answers

    What is the primary function of vitamin D in the small intestine?

    <p>Stimulation of calcium binding protein biosynthesis</p> Signup and view all the answers

    What is the primary form of vitamin D that is transported to the kidney for further hydroxylation?

    <p>Calcifediol</p> Signup and view all the answers

    What is the primary consequence of vitamin D deficiency in children?

    <p>Rickets</p> Signup and view all the answers

    What is the primary mechanism by which vitamin D regulates calcium levels in the blood?

    <p>Stimulation of calcium binding protein biosynthesis</p> Signup and view all the answers

    What is the primary form of vitamin D that is transported to the target organs, such as the intestine and bone?

    <p>Calcitriol</p> Signup and view all the answers

    What is the primary consequence of vitamin D deficiency in adults?

    <p>Osteomalacia</p> Signup and view all the answers

    What is the primary difference between fat soluble vitamins and water soluble vitamins in terms of their solubility?

    <p>Fat soluble vitamins are nonpolar and soluble in fat, while water soluble vitamins are polar and soluble in water.</p> Signup and view all the answers

    Which of the following vitamins is NOT stored in the liver?

    <p>Vitamin E</p> Signup and view all the answers

    What is the primary function of vitamin A in the body?

    <p>It is essential for vision and immune function</p> Signup and view all the answers

    What is the provitamin of vitamin A?

    <p>Carotene</p> Signup and view all the answers

    Which of the following sources is NOT a rich source of vitamin A?

    <p>Spinach</p> Signup and view all the answers

    What is the percentage of vitamin A stored in the liver?

    <p>95%</p> Signup and view all the answers

    What is the difference between vitamin A1 and vitamin A2 in terms of their activity?

    <p>Vitamin A2 has 40% of the activity of vitamin A1</p> Signup and view all the answers

    Which of the following is a characteristic of water soluble vitamins?

    <p>They are not stored in the body except vitamin B12</p> Signup and view all the answers

    What is the result of the increased keratinization of the skin due to vitamin A deficiency?

    <p>All of the above</p> Signup and view all the answers

    What is the recommended daily intake of vitamin A?

    <p>750 ug/day</p> Signup and view all the answers

    What is the source of vitamin D2?

    <p>Plants and yeast</p> Signup and view all the answers

    What is the result of chronic toxicity of vitamin A?

    <p>Hair loss and skin fissuring</p> Signup and view all the answers

    What is the precursor to vitamin D3?

    <p>7-dehydrocholesterol</p> Signup and view all the answers

    What is the daily requirement of vitamin D for normal adults?

    <p>100 I.U</p> Signup and view all the answers

    What is the effect of vitamin A deficiency on the conjunctiva?

    <p>Squamous metaplasia</p> Signup and view all the answers

    What is the source of vitamin D3?

    <p>All of the above</p> Signup and view all the answers

    Study Notes

    Metabolism of Vitamin D

    • Dietary vitamin D is absorbed from the small intestine and transported to the liver via chylomicrons.
    • In the liver, vitamin D is activated and metabolized to 25-hydroxycholecalciferol (calcifediol).
    • Calcifediol is transported to the kidney, where it undergoes further hydroxylation to form the hormone 1,25-dihydroxycholecalciferol (calcitriol).
    • Calcitriol is transported to target organs (intestine and bone) via vitamin D-binding protein.

    Functions of Vitamin D

    • Increases and regulates calcium and phosphate absorption from the small intestine.
    • Stimulates the biosynthesis of calcium-binding protein, which transports calcium to the blood.
    • Essential for bone mineralization (calcification).
    • Inhibits calcium and phosphate excretion in the urine.

    Vitamin D Deficiency

    • Occurs due to inadequate sun exposure, inadequate dietary intake, or defective renal tubular phosphate reabsorption.
    • Leads to rickets (in children) and osteomalacia (in adults), causing softening and deformities of bones.

    Vitamins

    • Organic substances essential for health and growth, but not synthesized in the body in sufficient quantities.
    • Needed in small amounts and must be obtained through diet.
    • Do not enter body structure or tissue structure.
    • Act as catalysts and are not oxidized to produce energy.

    Types of Vitamins

    • Fat-soluble vitamins (A, D, E, and K) and water-soluble vitamins (B and C).
    • Fat-soluble vitamins are nonpolar, require fat and bile salts for absorption, and are stored in the body.
    • Water-soluble vitamins are polar, easily absorbed, and not stored in the body (except for vitamin B12).

    Vitamin A

    • Present in animal products (fish, liver, oils, meats, eggs, cheese, and butter) and plant products (carotenes in carrots, tomatoes, and sweet potatoes).
    • Converted to vitamin A in the intestine and liver.
    • 95% is stored in the liver.
    • Has two forms: vitamin A1 (in animal products, high activity) and vitamin A2 (in fish and liver, 40% activity of A1).
    • Provitamin is carotene.

    Metabolism of Vitamin A

    • Absorbed from the intestine in the presence of fat and bile salts.
    • Transported to the liver through chylomicrons and lipoproteins.
    • Converted to retinol, which can be oxidized to retinal or retinoic acid, both having vitamin activity.

    Functions of Vitamin A

    • Required for visual function, particularly for rhodopsin in the retina.
    • Essential for health and growth, reproduction, mucus secretion, and maintaining differentiated epithelia.
    • Essential for bone formation and calcification.

    Deficiency of Vitamin A

    • Leads to night blindness, keratomalacia, xerophthalmia, and premalignant conditions.
    • Causes keratinization of the skin, blocking sebaceous glands, and squamous metaplasia.

    Toxicity of Vitamin A

    • Excess intake can cause drowsiness, headache, abdominal pain, vomiting, and skin desquamation in children.
    • Chronic toxicity leads to hair loss and skin fissuring.

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    Description

    Learn about the process of vitamin D metabolism, from absorption in the small intestine to activation in the liver and kidneys. Understand how it's transported and converted into its active form, calcitriol.

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