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1. VITAMIN- A
M.Prasad Naidu
MSc Medical Biochemistry, Ph.D,.

2. VITAMIN- A
 Structure
6C beta-ionine ring with 11C polyprenoid side chain with
alternate double bonds.
 Provitamin–beta carotene [Retinal+Retinal]
 Active forms 1.Retinol
2.Retinal
3.Retinoic acid

3. CH 3
CH 3H 3C
CH 3
CH 2OH
CH 3
VITAMIN A (RETINOL)
RDA: 0.7 mg
Poly isoprenoid side chain

5. VITAMIN A
 Retinol Retinal retinoicacid All-trans Retinal
common in circulation.
 11cis- Retinal form is present in rhodopsin.
 Active forms are heat stable and light sensitive.

6. VITAMIN A
 Sources
Animal –marine fish liver oils
Plant - mangopapayacarrot
 RDA – 1000 ug day
1 RE = 1ug of retinol = 0.6 ug of betacarotene

7. VITAMIN A

8. .
FUNTIONS
1. Retinal and Retinol vision
2. Retinoic acid –
cell differentiation
glycoprotein synthesis
reproduction.
3.Beta-carotene- Anti-oxidant

9. WALDS VISUAL CYCLE
 The Cyclic events that occur in the process
of vision is visual cycle. .
 Rhodopsin is a photoreceptor present in
retinal rod cells.
 Rhodopsin is a conjugated protein with 11-cis
retinal and protein opsin.

10. FUNCTIONS OF VIT A
WALDS
VISUAL CYCLE

12. DEFECIENCY
primary causes [dietary]
secondarycauses[malabsorption]
Results in
Night blindness
Conjunctival xerosis
Bitots spots
Corneal xerosis
keratomalasia
Blindness

13. .
 Toxicity of vit-A is either due to
1. over-dosage of vit-A supplements
2. excess dietary intake [
 As vitamin A is not excreted from the body it
isccumulated in liver producing toxic
effects
 Toxicity produces headache , nausea , vomitings
, liver damage alterations in the skin and mucous
membranes etc.

14. .
 Vit-A can be used to treat diseases where
epithelial surface is damaged.
 Retinoic acid acts on cell differentiation and
growth therefore used as a drug.
 It is used to treat diseases like Measles,
Acne, Psoriasis , Leukemia etc.

17. VISUAL CYCLE
meta-rhodopsin
Transducin Transducin [A]
PDE PDE [A]
CGMP GMP

18. VISUAL CYCLE
Decreased CGMP
closes Na+ channels in rod cell membrane
hyper polarization of rod cell membrane
generation of nerve impulse to visual cortex

19. VITAMIN D
 Structure
plants - Ergosterol Ergocalciferol [D2]
Active form in animals is calcitriol
UV

21. VITAMIN D
 Sources
1. sunlight
2. animal sources; fish liver oils eggs
3. plant sources
4. food fortification ; milk butter
 RDA
200-400 IU day

22. VITAMIN D
 Digestion absorption transport
Digested and absorbed in small intestine
using bile salts .
Vit-D is transported from intestine to
circulation by chylomicrons and stored in the
liver.

23. VITAMIN D
 Synthesis of vit-D
 Regulation of synthesis by Ca and PO4.
 Low calcium stimulates PTH secretion which
activates 1- hydroxylase

24. FUNCTIONS
Vit-D plays a major role in regulation of calcium
and phosphate levels by mainly acting on 3
different organs.
 Intestine ; increases absorption of Ca and PO4
 Bone ; increases deposition of CaPO4 thus
increasing mineralization of bones .
 Kidneys ; reabsorbs Ca and decreases Ca
excretion.

26. VITAMIN D
 Deficiency
Children ---Rickets
Adults ------ Osteomalacia

27. VITAMIN D
 Toxicity
hyper-vitaminosis D causes toxic effects
like de-mineralization , hyper-calcemia ,
renal calculi etc.

35. ABSORPTION AND TRANSPORT

36. IRON DEFICIENCY ANEMIA
 Laboratory findings
 Hypochromic microcytic
anemia
 ferritin ( 30 to 300
Nanogm/ml)
 serum iron (50 to175 µgm/dl)
 TIBC (300 to 350 µgm/dl)
 transferrin (200 to 400 mg/dl)
Spoon-shaped nails (koilonychia)

37. Dental fluorosis

42. THANK Q