FAT SOLUBLE VITAMINS
They are four types in vitamin
1.vitanmin A
2. vitamin D
3.vitamin E
4. vitamin K
vitaminA::
Chemistry it is an unsaturated primary alcohol (Retinol) chemically it is retinol structurally related to the plant pigment carotene Vit A is derived from B-carotene hence b-carotene is described as pro vitamin A It requires bile salts and fat for absorption
source::
chief sources are fish liver oil i.e.cod liver oil shark liver oil and liver oil milk cheese and egg vegetable oils do not contain vit A animal oil like ghee and butter are good sources vegetable and fruit like carrot tomato spinach mangoes etc are rich sources of Vit A
Storage:: It is stored mainly in the liver a little in the lungs and skin
Excretion:It is excreted through stools
Funcation::
It is essential for the body growth and weight it is very useful for health of the eyes skin epithelia and nervous system it aids in bone cell formation (along with vit D) fertility and resistance against cold (along with vit C) It is also essential for the formation of rhodopsin the light sensitive chemical substance in rods of retina
Deficiency:1.Eyes::
prolonged deficiency of Vit A results in night blindness This is due to absence of resynthesis of rhodopsin when exposed to light (Dark-adaptation test) Deficiency of vit A leads to degeneration of the lachrymal gland of the eye causing xerophthalmia its deficiency gives rise to red eyes and corneal ulcers
2.Alimentary system:
Epithelia degenerate and give digestive disturbances in vit A deficiency
3.Respiratory system::
Deficiency of vit A leads to increased susceptibility or respiratory diseases like cold pneumonia and tuberculosis it is therefore called an Anti-infective vitamin
4.Skeletal system::
vit A deficiency leads to slow and irregular growth of bone and teeth
5.Nervous system::
According to Mellanby vit A deficiency also adversely affects medullary sheaths of nerves
6.Fertility::
Vit A deficiency adversely affects the normal ovulation in rats This is not proved in the human Still it is used empirically to aid spermatogenesis in man and ovulation in woman
Hypervitaminosis:III effects are noticed in animal and man
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