Vitamins Doesnt metabolize to yield energy vital to

Vitamins

• Doesn't metabolize to yield energy. • -vital to life. • -group of substance turned out to have the particular metabolic activity. • - nitrogen –containing chemical substance called an amine { vital amine }.

*definition of vitamins : • -vital organic dietary substance that is not an energy producing CHO, fat , protein , needed in very small quantities to perform a particular metabolic function. • It cant be manufactured by the body & therefore must be supplied in food.

** classification of vitamins : • • Fat soluble vitamins : A, D, E, K - they can be stored. -associated with lipid. 2 - water soluble vitamins : -B complex family , C -they cannot be stored. -vitamins B act as co-enzyme in cell metabolism. • -vita mine C is vital structural agent.

Fat soluble vitamins • ** vitamin A : • has specific function in the retina of the eye. • found only in animal food sources. • deposited in the liver , kidneys , lungs , & fat tissue. • found in egg yolk , liver , pigment of carrots.

absorption of vit A under assistance of : • bile salts so obstruction of bile duct , infectious hepatitis & liver cirrhosis = decrease the absorption of vit A. • pancreatic lipase. • Dietary fat stimulate bile release for effective absorption of vitamin A. • absorption of vitamin A through small intestine to blood stream then to the lymphatic system then to liver 90% stored at liver

functions of vitamin A : • • has role in visual adaptation to light & dark. has role in covering epithelial tissue. reproductive function. vitamin A deficiency lead to night blindness , this condition usually cured in about 30 minutes by an injection of vitamin A. • vitamin A is necessary to build & maintain healthy epithelial tissue & act as barrier to infections. • the epithelium include not only the outer skin , but also the inner mucous membrane.

• without vitamin A the epithelial cells become dry & flat , then gradually harden to form keratin. • keratin is a protein that forms dry scale like tissue , normal in the nail & hair , but abnormal in the skin & mucous membrane.

** deficiency of vitamin A lead to : • eye : cornea dries , blindness. • respiratory tract : dryness of epithelium & cracked of salivary glands. • gastro intestinal system : decrease of mucous membrane secretion affect on digestion & absorption. • genitourinary tract : vaginal infection & dryness of vaginal mucosa , urinary tract infection , stone formation. • integmentary function : skin become dry & scaly

• • tooth formation : decrease development of teeth ** N. B : vitamin A is essential for bone growth. Vitamin A is necessary to support normal sexual maturation during adolescence period. -sever deficiency of vitamin A lead to sterility

** vitamin A deficiency due to • in-adequate dietary intake. • poor absorption due to lack of bile. • disease of the liver or intestine that obstruct its metabolism & absorption

** hyper vitaminosis: • • • joint pain thickening of long bone loss of hair jaundice liver affection , portal hyper tension & ascites ** source of vitamin A : animal source [ liver , kidney , butter egg yolk ] • plant source : green vegetables , fruit