HSS2342 Nutritional Determinants of Health Final Exam Review 100%

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HSS2342 Nutritional Determinants of Health Final Exam Review The Fat-Soluble Vitamins: A, D, E, K Vitamin A  First fat-soluble vitamin recognized  Precursor is beta-carotene  Three diffe... rent active forms in body o Retinol  Supports reproduction  Major transport and storage form o Retinal  Active in vision o Retinoic acid  Acts as a hormone: regulates cell differentiation, growth, and embryonic development  Foods derived from plants contain carotenoids, some of which can be converted into vitamin A  Beta carotene can be split to form retinol in the intestine and the liver  Beta carotene’s absorption and conversion are significantly less efficient than those of retinoids  Conversion of retinol to retinal is reversible, but the further conversion of retinal to retinoic acid is irreversible  Several proteins are involved in the digestion and absorption of vitamin A o After absorption via lymph system, it eventually arrives at liver, where it is stored o Then binding protein called retinol-binding protein (RBP) picks it up and carries in it the blood o Cells that use vitamin A have special receptors for it, and its action in each cell may differ depending on the receptor on the cell  For example, retinoic acid can stimulate cell growth in the skin and inhibit cell growth in tumors  Roles in the body o Promoting vision  Helps maintain cornea  Participates in conversion of light energy into nerve impulses at the retina o Protein synthesis and cell differentiation, thereby maintaining the health of epithelial tissues  Helps cells specialize into their respective functions  Mucous membranes o Supporting reproduction and regulating growth  Retinal participates in sperm development  Supports normal fetal development during pregnancy  Growth of children; role in bone remodelling o Regulation of gene expression [Show More]

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