Friday, August 25, 2006

Vitamin A

Vitamin A

A Vitamins are an organic molecule which are required by a living organism in minute amounts for proper health. An organism deprived of all sources of a particular vitamin will eventually suffer from disease symptoms specific to that vitamin. Vitamins can be classified into two and they are water soluble, which means they dissolve easily in water and fat soluble, which means they are absorbed through the intestinal tract with the help of lipids. A vitamin forms an important nutrient of diet.

Functions: A Vitamins

The functions of a vitamin are as follows:
Vision: The retina is located at the back of the eye. When light passes through the lens, it is sensed by the retina and converted to a nerve impulse for interpretation by the brain. Retinol is transported through A Vitamins to the retina via the circulation, where it moves into retinal pigment epithelial cells.

Regulation of gene expression: Retinoic acid (RA) and its isomers act as hormones to affect gene expression and thereby influence numerous physiological processes. Through the stimulation and inhibition of transcription of specific genes, retinoic acid plays a major role in cellular differentiation, the specialization of cells for highly specific physiological roles. Most of the.....

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