FSHN 360 Final Exam 2023 Graded A

FSHN 360 Final Exam 2023 Graded A fat soluble vvitamins - structurally similar to sterols or FA micells, passive diffusion, chylomicrons in circulation circulatory transporters no membrane transporter stored/toxic/don't need daily toxicity is only really true for Vitamin A and Vitamin D to some extent vitamin A - main form: all-trans retinol can also be oxidized to retinal (ketone) or oxidized once more to retinoic acid sources of vitamin A - animal- preformed, retinyl esters, FA with ester linkage to alcohol plant- provitamin, carotenoids, metabolized to become active vitamin A lecitin retinol acyl transferase - enzyme in the enterocyte that re-esterifies retinol to retinyl ester retinyl ester hydrolase - enzyme in the GI tract that hydrolyzes a retinyl ester into retinol and FA retinyl ester - storage form of vitamin A 100 % absorbed retinol binding protein - a protein that is necessary to transport vitamin A from the liver to other tissues joins TTR to help retain retinol in circulation Transthyretin (TTR) - protein that is necessary to help transport vitamin A from the liver to the tissue joins RBP to help retain retinol in circulation Beta-carotene monooxygenase - enzyme in the enterocyte that transforms beta-carotene into 2 retinal beta-carotene - plant form of vitamin A 2 retinols linked together approximately 1/12 becomes active vitamin A retinol activity equivalents (RAE) - a measure of vitamin A activity; the amount of retinol that the body will derive from a food containing preformed retinol or its precursor, beta-carotene 1 RAE= 1 microgram all-trans retinol or 12 micrograms of beta-carotene function of vitamin A - visual cycle (retinal), cellular differentiation (RA), whole body growth (RA), reproductive function (retinol) visual cycle - a function of Vitamin A taking retinol and transforming it into 11-cis-retinal in the eye cells, 11-cis-retinal is then combined with opsin to become rhodopsin which is activated by light to become metarhodopsin metarhodopsin translates light to the brain via the optic nerve and then opsin is released and becomes all-trans retinal and the cycle then continues opsin - protein that combines with 11-cis-retinal in the eye cells to create rhodopsin vitamin A deficiency - compromised visual cycle night blindness leading to keratomalacia stunted growth infection in GI tract Vitamin A and Cell Differentiation - Retinoic Acid decreases cell proliferation, increases differentiation, and increases apoptosis enterocytes depend on this process controlled through gene expression RA receptors can turn on genes by binding to DNA and turning on transcription examples: PEPCK, growth hormone Vitamin A and growth - Vitamin A deficiency impairs growth, which can be stimulated with retinol or retinoic acid Retinoic acid stimulates growth by increasing expression of growth receptors on cell surface vitamin A deficiency creates stunted growth vitamin A and reproduction - required for both male and female reproductive health low vitamin A= lack of reproduction high vitamin A= taratogen, causes birth defects vitamin A toxicity - Hypervitaminosis A, birth defects Hypervitaminosis A - excess amounts of vitamin A affects the liver because that is where is stored causes liver dysfunction severe: coma and death achieved through supplementation of pharmaceuticals can cause birth defects accutane - treats cystic acne 12-cis Retinoic Acid can cause birth defects in pregnant women Retin-A - all-trans Retinoic Acid wrinkle cream because it is applied topically it is not toxic Acute Promyelocytic Leukemia - type of leukemia that can be treated with all-trans RA Cellular retinol-binding protein (CRBP) - protein in the cytosol of cells that binds to retinol cellular retinal-binding protein (CRALBP) - protein in the cytosol of cells that binds to retinal cellular retinoic acid binding protein (CRABP) - protein in the cytosol of cells that binds to retinoic acid retinoic acid receptor (RAR) - receptor in the nucleus of cells that binds to retinoic acid retinoid x receptor (RXR) - receptor in the nucleus that is activated by 9-cis-RA and binds to the RAR and retinoic acid complex which then binds to DNA sequences to turn genes on vitamin D - conditionally essential vitamin that is synthesized from cholesterol in a reaction that is sunlight dependent food sources not abundant fortification with D3 helps with calcium homeostasis 7-dehydrocholesterol - form of vitamin D that is found in the skin and is transformed into cholecalciferol (D3) by sunlight cholecalciferol - vitamin D3 form of vitamin D made from 7-dehydrocholesterol by sunlight form of D3 found in the diet, as well as fortified foods and supplements 25-hydroxycholecalciferol - form of vitamin D that is made in the liver from D3 requires the enzyme 25-hydroxylase found in circulation bound to the vitamin D binding protein vitamin D binding protein - protein that binds to 25D in circulation 1,25-dihydroxycholecalciferol - active form of vitamin D made from 25-hydroxycholecalciferol made in the kidney requires the enzyme 1-hydroxylase function of vitamin D - regulates calcium homeostasis decreases proliferation increases differentiation increases apoptosis (promotes normal cell cycle) immune system health how does vitamin D regulate calcium? - 1. increasing absorption in the enterocytes 2. increasing reabsorption in the kidneys (PTH) 3. increasing resorption from the bone (PTH) vitamin D receptor (VDR) - binds to 125D in the enterocyte to bring it into the nucleus vitamin D response element (VDRE) - RXR and 125D and VDR complex bind here to initiate transcription 'parking spot' AGGTCA(X)3AGGTCA TRPV6 - a Ca+2 channel at the apical membrane of enterocytes induced by 125 D, increased abundance of transporters calbindin - a calcium-binding transport protein that requires vitamin D for its synthesis transport protein for calcium inside enterocyte induced by 125 D PMCA - transport protein on the basal membrane of enterocyte that transports calcium into circulation induced by 125 D vitamin D deficiency - can cause cancer or MS rickets (soft bones) in children osteomalacia (adult rickets) vitamin D toxicity - high upperlimit adequate intake can be toxic at very high doses hypercalcemia hypercalcemia - too much calcium in blood leads to calcification of soft tissue vitamin D assessment - measure 25-hydroxycholecalciferol in the blood type 2 diabetes and vitamin D - nephropathy causes the loss of 25D and DBP in the urine creates vitamin D deficiency vitamin K active form - 3 forms: phylloquinone (plants) menaquinone (animals + bacteria) menadione (synthetic) active form: dih