NUTR 120 Lecture Notes - Lecture 22: Vitamin A Deficiency, Vanishing Twin, Visual Phototransduction
Document Summary
Beta-carotene mangos, oranges (orange colored fruits and veggies. Rda: 700mcg/day for women, 900mcg/day for men (rae: retinoic acid equivalents) Retinol is absorbed in chylomicron vascular system liver beta carotene transported in vldl . Retinyl ester (retinol attached to a fatty acid) retinol. Retinol is absorbed in chylomicron vascular system liver (stored in liver as retinyl ester) beta carotene transported in vldl adipose tissues (beta-carotene stored in adipose) Functions of vitamin a: vision visual cycle, epithelial cell function (skin, lungs, gi tract, cornea, growth (bone remodelling, reproduction: woman deficient in vitamin a causes fetal resorption, in men causes decreased sperm formation. Light energy enters the eye rhodopsin opsin opsin signal to the brain and conversion to retinal. Xerophthalmia: deficiency of vitamin a in corneal epithelia. Normal epithelial tissue is moist and lubricating with a mucus layer. Vitamin a deficient epithelial tissue with be hard and dry with a keratin layer (from keratinization)
