Flashcards in Wk1 Fat soluble vit/minerals/elect pt 1 Deck (47):
Define EAR (Estimated Average Requirement)
Average daily nutrient intake level estimated to meet the requirements of of half of the healthy members of a particular life stage and gender group
Define RDA (Recommended Daily Allowance)
Average daily dietary nutrient intake level sufficient to meet the nutritional requirements of nearly all (97-98%) healthy persons in a particular life stage and gender group
Define Tolerable Upper Limit:
Risk of "overdose" is approx. 0.1%
Biologically active form of vit A:
-branched polyunsaturated acyle chain
Three things all-trans-retinol can be converted to:
2. carboxylic acid
3. ester w/ fatty acid (eg. palmitate)
Three dietary forms of vit A:
1. retinyl palmitate
Vit A metabolite that can be transported in blood with albumin:
Vit A metabolites that are transported in chylomicrons:
Retinyl-fatty acid esters
Reservoir for vit A storage in liver:
retinal cycle in photoreceptors?
cis-retinal + opsin = rhodopsin
rhodopsin + UV light = opsin + tras-retinal
trans-retinal --> G-protein rec. --> closes Na+ channels --> hyperpolarization of rod cell --> signals neuron
trans-retinal recycled back to cis-retinal
4 roles of retinoic acid ligand based transcription factors (RAR, RXR, PPAR):
1. differentiation of goblet cells (inhibits keratinization)
2. apoptosis of cancer cells
3. maturation of dendritic cells
4. recruitment of antibody secreting cells to small intestine
Vit A metabolites that act as antioxidants:
carotenes (double bonds bind free radicals)
Bitot's spots in the eye?
Vit A deficiency
Dry eye due to keratinization?
due to vit A deficiency
Vit E form with SATURATED 16-C acyl chains:
Vit E form with polyUNsaturated 16-C acyl chains:
Vit E absorption and distribution parallels _____?
fat digestion and absorption
Vit E functions?
1. lipid bilayers
2. intracellular plasma membranes
3. cellular oxidative stress defense
Vit that can inhibit Vit K absorption and metabolism:
Vit E deficiency: Causes? Symptoms?
-short bowel syndrome
-ataxia, loss of vibratory sense
Main form of dietary vit K:
green leafy vegetables
Vit K produced by fermentation:
Vit K absorption paralells _____.
Vit K stored in _______.
cell membranes of lung, kidney, bone marrow, adrenal glands
Coumadin blocks what enzyme?
vit k epoxide reductase
Clotting factors reliant on vit K dependent carboxylation:
Main circulating form of vit D:
Biologically active form of vit D:
Where does vit D get activated:
**in response to PTH
Enzyme in kidney responsible for activating vit D:
1-a-hydroxylase (+ PTH)
Ca++ channel on brush border:
Vit D deficiency characterized by seizures, growth retardation, failure of bone mineralization (osteomalacia):
Most toxic vitamin?
Vit associated with reduced colorectal carcinoma:
Most abundant metal ion in the body:
HOw does Ca++ get across basolateral membrane?
Transcellular movement of Ca is regulated by?
Pericellular transport of Ca is regulated by?
Intracellular signalling by calcium is mediated by?
How does Ca decrease cholesterol?
traps bile salts and fatty acids in undigestable soaps --> diverts cholesterol to bile salt synthesis
Saturable transport of Mg+ across brush border?
Basolateral transport of Mg+?
1. 2Na+ / Mg2+ antiporter
2. 2K+ / 3Na+ ATPase (creates favorable Na conc for #1 above)
Functions of Mg++?
Best measurement of Mg++?