FNDH 620 Final Exam | 100% Correct | Verified | 2024 Version

True or False Vitamins: - cannot be made in the body - noncaloric - required in small amounts (mg and mcg) - TRUE Vitamins: - cannot be made in the body - noncaloric - required in small amounts (mg and mcg) What 3 forms can vitamin A take? - - retinol (alcohol) - retinal (aldehyde) - retinoic acid (acid form from retinal) What form of vitamin A is normally found in blood and tissues? - Retinyl Palmitate What form of vitamin A is found in plants? - Previtamin A - carotenoid structure that includes the carotenes and xanthophylls - found in plants - needs to be converted to active vitamin A What is the most potent form of vitamin A? - Beta caroteneWhere can retinyl esters be found? - Animal Products *only* Where can vitamin A be found? - Fortified milk and milk products Where can previtamin A carotenoids be found? - Plant sources - orange and dark green vegetables Vitamin A containing micelles form and traverse the enterocyte plasma membrane by what type of diffusion? - Passive Diffusion What two things are needed in the digestion of vitamin A? - Bile and Fat Beta-carotene and other carotenoids can be converted to retinol by what means? - Beta-carotene and other carotenoids can be converted to retinol by cleavage of the central double bond When beta-carotene is cleaved, how many molecules of retinal does it make? - 1 beta-carotene = 2 retinal Retinyl, retinyl esters, and carotenoids are packaged into what and transported where? - Retinyl, retinyl esters, and carotenoids are packaged in *chylomicrons* and transported in the *lymphatic system*. Vitamin A and carotenoids are metabolized where and as what? - Vitamin A and carotenoids are metabolized in the liver as chylomicron remnants. Retinoic acid is absorbed and transported to which organ bound to what protein? - Retinoic acid is absorbed and transported to the liver bound to albumin. The liver stores 90% of which vitamin? - vitamin A What are the functions of vitamin A & Carotenoids? - - Improves vision- Cell differentiation & cell proliferative activity - Fights cancer - Development of embryo tissue - Synthesis of glycoproteins - Reproductive processes - Antioxidant capacity - Bone development and maintenance - Provides immunity How is vitamin A essential to our vision? - - retinol is transformed into 11-cis retinal through a series of reactions - 11-cis retinal combines with the protein opsin forming rhodopsin - Rhodopsin + light changes the conformation of the protein which begins a cascade of events leading to the generation of an action potential - This action potential sends neural impulses to the optic center of the brain translating it into images What are the 2 nuclear receptors that work with vitamin A on a molecular level? - RAR & RXR Vitamin A is beneficial for all cancers but... - lung cancer Vitamin A is involved in sperm development and differentiation, without it, what happens? - Without RARγ, males are sterile If a female is low or deficient in vitamin A, what could happen? - deficiency: inability of implantation of the egg low: may allow implantation but may end in a miscarriage; various birth defects Vitamin A is excreted in _____ & _____. - Vitamin A is excreted in the bile (70%) and urine (30%).RDA of vitamin A for men - 900 mcg/day RDA of vitamin A for women - 700 mcg/day 12 mcg beta-carotene = ??? mcg of retinol - 12 mcg beta-carotene = 1 mcg of retinol Vitamin A deficiency is the leading cause of ___________ in children worldwide. - Vitamin A deficiency is the leading cause of *non-accidental blindness* in children worldwide. Diseases caused by vitamin A deficiency - - night blindness - xerophthalmia - bitot spot