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Outline the Functions of vitamin A in Human Nutrition

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1.Maintaining the integrity of epithelial tissues.
The epithelial cells secret mucus which protect them from infections. If vitamin A is
deficient, these cells secret a protein known as keratin instead. Keratin is a normal
body compound, the protein of hair and nails, but if it fills the epithelial cells, they
become hard, a condition referred to as keratinization. The cells cannot perform
their job and they die, leaving the surface unprotected from infections. Epithelial
tissues include the lining of the lungs, stomach, intestines, vagina, urinary tract, the
bladder as well as eyes and skin.

2.Vision
Vitamin A is best known for its role in promoting normal vision. It restores the ability
to see in dim light after eyes have been blinded by strong light, a process referred to
as dark adaptation. There is a colored compound in the retina of the eye known as visual purple or rhodopsin that gets beached when light falls on it. In order for one to see again the visual purple must be regenerated again. As the vitamin A is part of the visual purple, the eye depends on adequate supply of vitamin A to constantly regenerate the visual purple. If vitamin A supply is low, lag occurs before the eye sees again. This lag in the recovery of night vision termed as night blindness indicates vitamin A deficiency.

3.Growth
Animals deprived of vitamin A cease to grow after vitamin A reserves are depleted.
Growth failure will occur before most of the other symptoms occur except night
blindness. Vitamin A seems to be involved in re-modeling of the end of the bones,
which is a prerequisite to the laying down of a new bone. In the jawbone, vitamin A
promotes normal tooth spacing. Vitamin a deficiency occurs as a result of growth
retardation due to impairment in skeletal formation.

4.Reproduction
Vitamin A is necessary for normal reproduction. Studies have showed that the
absence of vitamin A in male rats leads to a failure to produce sperms. The retinol
form of vitamin A stimulates normal reproduction deficiency of vitamin a leads to
degeneration of germinal epithelium leading to sterility in males.
Other functions of vitamin A include:
- Production of proteins found in mucus secretions.
- Wound healing.
- Improves appetite (healthy taste buds).

Titany answered the question on November 8, 2021 at 05:02

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Outline the Functions of vitamin A in Human Nutrition

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