Vitamin A Deficiency
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Questions and Answers

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

  • Vitamin E (correct)
  • Vitamin D
  • Vitamin K
  • Vitamin A

    • What is the characteristic of fat-soluble vitamins in terms of absorption?

  • Need fat and bile salt for absorption (correct)
  • Absorbed only in the presence of water
  • Can be absorbed without fat
  • Easy absorption

    • Which of the following is a polar vitamin?

  • Vitamin A
  • Vitamin E
  • Vitamin C (correct)
  • Vitamin D

    • What is the provitamin of Vitamin A?

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

    What is the characteristic of water-soluble vitamins in terms of excretion?

    <p>Excreted in the urine, depending on the renal threshold</p> Signup and view all the answers

    Which of the following is a characteristic of Vitamin A1?

    <p>Has one double bond between C5 and C6</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

    Which of the following is a characteristic of Vitamin A2?

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

    What is the primary reason why vitamins are required in the diet?

    <p>The body is unable to synthesize them in sufficient quantities</p> Signup and view all the answers

    What is the result of the conjunctiva and other epithelia undergoing squamous metaplasia in vitamin A deficiency?

    <p>Premalignant conditions</p> Signup and view all the answers

    What is the role of vitamins in the body?

    <p>They act as catalysts and are not oxidized to give energy</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 D3?

    <p>Fish, liver, oil, meats, butter, eggs, and milk</p> Signup and view all the answers

    Why are vitamins required in small amounts?

    <p>They are cofactors for enzymatic reactions</p> Signup and view all the answers

    What is the characteristic of vitamins in terms of their body structure?

    <p>They do not enter into the body structure</p> Signup and view all the answers

    What is the provitamin of vitamin D3?

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

    What is the primary function of vitamins in the body?

    <p>To support growth and development</p> Signup and view all the answers

    What is the result of excess vitamin A intake in children?

    <p>Drowsiness, headache, and abdominal pain</p> Signup and view all the answers

    What is the daily requirement of vitamin D for infants, children, pregnant, and lactating women?

    <p>400 I.U</p> Signup and view all the answers

    Why are vitamins needed in the diet?

    <p>They are needed to support growth and health</p> Signup and view all the answers

    What is the result of vitamin A deficiency on the skin?

    <p>Increased keratinization</p> Signup and view all the answers

    What is the characteristic of vitamins in terms of their oxidation?

    <p>They are not oxidized to provide energy</p> Signup and view all the answers

    What is the primary difference between vitamins and other nutrients?

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

    Where is vitamin D synthesized in the human body?

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

    What is the role of vitamin A in visual function?

    <p>Formation of rhodopsin pigment in the retina</p> Signup and view all the answers

    What is the protein that transports vitamin A in the blood?

    <p>Retinol-binding protein (R.B.P.)</p> Signup and view all the answers

    Where is retinol converted to retinal and retinoic acid?

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

    What is the consequences of vitamin A deficiency?

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

    What is the form of vitamin A that is transported in chylomicrons?

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

    What is the role of rhodopsin in the retina?

    <p>Conversion of light into nerve impulses</p> Signup and view all the answers

    Where is vitamin D activated and metabolized to 25-hydroxycholecalciferol?

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

    What is the function of vitamin D in regulating calcium and phosphate absorption?

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

    What is the consequence of bleaching of rhodopsin?

    <p>Reduced vision in low light conditions</p> Signup and view all the answers

    What is the consequence of vitamin D deficiency in children?

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

    What is the role of vitamin A in bone health?

    <p>Calcification of bones</p> Signup and view all the answers

    What is the function of vitamin D in bone health?

    <p>Stimulate mineralization of bones</p> Signup and view all the answers

    What is the result of inadequate sun exposure on vitamin D levels?

    <p>Decreased vitamin D levels</p> Signup and view all the answers

    What is the effect of vitamin D deficiency on calcium and phosphate levels?

    <p>Decreases calcium and phosphate levels</p> Signup and view all the answers

    Study Notes

    Vitamin A

    • Deficiency of vitamin A causes:
      • Night blindness
      • Keratomalacia (softening of the cornea, which may ulcerate and cause blindness)
      • Xerophthalmia (dry, rough, and keratinized conjunctiva and cornea)
    • Recommended daily intake: 750 μg/day
    • Functions:
      • Required for visual function (rhodopsin in the retina contains vitamin A and protein)
      • Essential for health and growth, normal reproduction, mucus secretion, and maintaining differentiated epithelia
      • Essential in the formation of bones and calcification of bones

    Vitamin A Metabolism

    • Vitamin A and its provitamin (carotene) are absorbed from the intestine in the presence of fat and bile salts
    • Transported to the liver through chylomicrons (lipoproteins containing VLDL, LDL, and HDL)
    • In the liver, carotene is converted to retinol, which can be oxidized to an aldehyde (retinal) or a carboxylic acid (retinoic acid)

    Vitamin D

    • Synthesized in the skin by the action of ultraviolet light on the precursor 7-dehydrocholesterol
    • Present in fish, liver, oil, meats, butter, eggs, and milk
    • Daily requirement:
      • 100 I.U (2.5 μg) for normal adults
      • 400 I.U for infants, children, pregnant, and lactating women
    • Functions:
      • Increases and regulates calcium and phosphate absorption from the small intestine
      • Essential for mineralization of bones (calcification of bones)
      • Inhibits calcium and phosphate excretion in the urine

    Vitamin D Deficiency

    • Occurs due to inadequate sun rays, foods rich in vitamin D, and defect of renal tubular phosphate reabsorption
    • Deficiency leads to:
      • Rickets (in children): defect in long bones calcification, leading to softening and deformities of bones
      • Osteomalacia (in adults): defect in calcification or mineralization of the organic matrix of bone

    Vitamins in General

    • Organic substances that are not synthesized in the body in sufficient quantities to meet the body's requirements
    • Essential for health and growth
    • Needed in small amounts
    • Must be taken in food (may not be formed in the body)
    • Do not enter into the body structure (or tissue structure)
    • Act as catalysts and are not oxidized to give energy
    • Classified into fat-soluble vitamins (A, D, E, and K) and water-soluble vitamins (B and C)

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    Description

    This quiz covers the effects of vitamin A deficiency, including night blindness, keratomalacia, and skin changes.

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