Vitamin A Deficiency

Study Flashcards Play Quiz

Questions and Answers

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

Vitamin E

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

Need fat and bile salt for absorption

Which of the following is a polar vitamin?

Vitamin C

What is the provitamin of Vitamin A?

Carotene Signup and view all the answers

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

Excreted in the urine, depending on the renal threshold Signup and view all the answers

Which of the following is a characteristic of Vitamin A1?

Has one double bond between C5 and C6 Signup and view all the answers

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

95% Signup and view all the answers

Which of the following is a characteristic of Vitamin A2?

Has 40% of Vitamin A1 activity Signup and view all the answers

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

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

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

Premalignant conditions Signup and view all the answers

What is the role of vitamins in the body?

They act as catalysts and are not oxidized to give energy Signup and view all the answers

What is the recommended daily intake of vitamin A?

750 ug/day Signup and view all the answers

What is the source of vitamin D3?

Fish, liver, oil, meats, butter, eggs, and milk Signup and view all the answers

Why are vitamins required in small amounts?

They are cofactors for enzymatic reactions Signup and view all the answers

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

They do not enter into the body structure Signup and view all the answers

What is the provitamin of vitamin D3?

7-dehydrocholesterol Signup and view all the answers

What is the primary function of vitamins in the body?

To support growth and development Signup and view all the answers

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

Drowsiness, headache, and abdominal pain Signup and view all the answers

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

400 I.U Signup and view all the answers

Why are vitamins needed in the diet?

They are needed to support growth and health Signup and view all the answers

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

Increased keratinization Signup and view all the answers

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

They are not oxidized to provide energy Signup and view all the answers

What is the primary difference between vitamins and other nutrients?

Vitamins are essential for health and growth Signup and view all the answers

Where is vitamin D synthesized in the human body?

Skin Signup and view all the answers

What is the role of vitamin A in visual function?

Formation of rhodopsin pigment in the retina Signup and view all the answers

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

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

Where is retinol converted to retinal and retinoic acid?

Liver Signup and view all the answers

What is the consequences of vitamin A deficiency?

All of the above Signup and view all the answers

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

Retinol Signup and view all the answers

What is the role of rhodopsin in the retina?

Conversion of light into nerve impulses Signup and view all the answers

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

Liver Signup and view all the answers

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

Increase biosynthesis of calcium-binding protein Signup and view all the answers

What is the consequence of bleaching of rhodopsin?

Reduced vision in low light conditions Signup and view all the answers

What is the consequence of vitamin D deficiency in children?

Rickets Signup and view all the answers

What is the role of vitamin A in bone health?

Calcification of bones Signup and view all the answers

What is the function of vitamin D in bone health?

Stimulate mineralization of bones Signup and view all the answers

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

Decreased vitamin D levels Signup and view all the answers

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

Decreases calcium and phosphate levels 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)

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.