B12 Flashcards
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| 5171370672 | B12 = | cobalamin | 0 | |
| 5171372801 | B12 is composed of | Macrocyclic ring (corrin) atom of cobalt in center | 1 | |
| 5171377292 | attached to the marocyclic ring and cobalt center are one of the following | • CN = cyanocobalamin • OH=hydroxocobalamin • H2O=Aquocobalamin • NO2= Nitrocobalamin • 5'-adenosyl=adenosylcobalamin* - coenzyme • -CH3=methylcobalamin* - coenzyme | 2 | |
| 5171379253 | Food sources | Animal products • derive their cobalamin from micro- organisms • meat, poultry, fish, shellfish, eggs, milk, milk products Supplements (cyanocobalamin and hydroxocobalamin) | 3 | |
| 5171386674 | B12 binds to | R protein first to move from the stomach into the SI | 4 | |
| 5171392178 | Once R protein with B12 reaches the duodenum | R protein is hydrolyzed by proteases (B12 is released) | 5 | |
| 5171394987 | R protein breakdown can be inhibited by | pancreatic insufficiency | 6 | |
| 5171418991 | After being released by R protein B12 is bound to | intrinsic factor in the proximal intestine | 7 | |
| 5171422202 | B12 bound to intrinsic factor travel to | the ileum and is then bound to receptors to be slowly absorbed | 8 | |
| 5171424757 | B12 is stored in the | liver | 9 | |
| 5171428879 | Enzymatic reactions requiring B12 | methionine synthesis Propionyl CoA oxidation pathway (mitochondrial mutase) | 10 | |
| 5171440363 | B12's neurological function | development and maintenance of myelin (SAM) | 11 | |
| 5171455167 | Methylmalonyl CoA mutase | converts L-methylmalonyl CoA generated from propionyl CoA to succinyl CoA | 12 | |
| 5171459987 | propionyl CoA is generated from the oxidation of | odd chain fatty acids amino acids: methionine, isoleucine, leucine | 13 | |
| 5181580002 | cobalamin deficiency | methylmalonyl CoA and methylmalonic acid (MMA) accumulate; see rise in blood and urine | 14 | |
| 5181583647 | Metabolism turnover | .1% / day loss of vitamin due to fecal loss | 15 | |
| 5181585598 | RDA | 1 microgram per day | 16 | |
| 5181586609 | UL | None | 17 | |
| 5181589379 | Elderly need to consume a synthetic source due to | high incidence of achlorydia | 18 | |
| 5181590160 | B12 deficiency | inadequate absorption is primarily responsible inadequate intake is rare but seen among vegetarians (strict vegans) | 19 | |
| 5181596808 | deficiency occurs in stages | low serum concentrations then low cell concentrations decreased DNA synthesis | 20 | |
| 5181598215 | Megaloblastic Anemia | Anemia may respond to mega doses of folate | 21 | |
| 5181599767 | Pernicious anemia | occurs with lack of intrinsic factor (oral B12 will not respond) | 22 | |
| 5181601488 | Neuropathy | Undetected Vitamin B12 deficiency leads to neuropathy (10+ years) tingling/numbness motor weakness No response to folate therapy | 23 | |
| 5181605611 | neuropathy cause | related to availability of methionine for SAM | 24 | |
| 5181608923 | SAM is required for | essential for myelin maintenance and thus neural function | 25 | |
| 5181611570 | B12 deficieny is related to | impaired absorption | 26 | |
| 5181611571 | Achlorydia | absence of hydrochloric acid in the gastric secretions. corrected with synthetic source | 27 | |
| 5181613444 | Lack of IF secretion | gastrectomy and destruction of gastric mucosa • treat with pharmacologic amounts of Vit B12 | 28 | |
| 5181614981 | decreased absorptive surface | ileal resection celiac and tropical sprue ileatis | 29 | |
| 5181616668 | Toxicity | none | 30 | |
| 5181618778 | Assessment | serum B12 RBC changes (larger presence of immature RBC) Elevated urinary MMA | 31 |