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Block6 ETOH
Block 6 ETOH - the fourth food group
Question | Answer |
---|---|
What is the fourth food group? | Ethanol |
What is the first enzyme to act on EtOH? | Alcohol dehydrogenase breaks it into acetaldehyde |
What enzyme works on acetaldehyde? | acetaldehyde broken to acetate by aldehyde dehydrogenase |
Where is ethanol metabolized? | the liver |
What builds up with excessive EtOH metabolism? Problem? | NADH - which shifts the biosynthetic pathways toward lactate/lactic acid production and away from pyruvate/glucose production |
What is the real toxin in ETOH metabolism? | cheap wine...or acetaldehyde |
What is the second route of ethanol oxidation? | microsomal ethanol oxidizing system (MEOS) |
What is the principle enzyme used in MEOS? What does it use as an electron donor and acceptor? | cytochrome P450 uses NADPH as electron donor and O2 as acceptor |
How many kilocalories per gram are in ethanol | 7 Kcal/gram |
What are the toxic effects of alcohol metabolism? | 1. acute effects of NADH/NAD+ shift biosynthetic pathways 2. wake up next to a fat girl 3. toxic effects of acetaldehyde on liver |
What is the fast step in EtOH metabolism? | EtOH + NAD+ catalyzed by alchol dehydrogenase (ADH) creates acetaldehyde and NADH |
What is the Slow or second step? What will inhibit this step? | Acetaldehyde + NAD+ catalyzed by aldehyde dehydrogenase to acetate + NADH inhibited by Disulfiram |
Three conditions caused by acute alcoholism? | hypoglycemia, lactate acidosis, hyperurcemia |
If a fasting person drinks heavily, what possible biosynthetic pathways are altered? | limited gluconeogenesis causes hypoglycemia lacticacidemia from excess NADH left shifting pathway lactate inhibits excretion of uric acid = hyperuricemia |
What are two necessary precursors for gluconeogenesis? | alanine and glycerol |
What makes acetaldehyde so dangerous to the internal environment? | It binds to macromolecules containing NH2, thiols etc.. to form adducts. Adducts destroy the original activity of the macromolecule |
Why is protein synthesis and secretion damaged by chronic alcoholism? | adduct formation with tubulin(microtubules) and amino acids impairs it. |
Why is adduct formation with glutathione so damaging? | Glutathione scavenges free radicals. When mitochondria are damaged, the ROS become worse |
What makes alcoholics pack on the pounds? | damaged mitochondria uncouple oxidative phosphorylation - Fatty acid oxidation decreases, only fatty acid synthesis occurs |
What is seen with alcohol damage to the brain? | Ataxia cognitive damage nystagmus |
What is seen in the liver? | accumulationof collagen-type layers, disappearance of elastic fibers, parenchymal damage Release of AST/ALT |
What vitamin is most affected by alcohol? Why? | Thiamine (B1) absorption in the GI tract is inhibited |
Excess acetate from acetaldehyde is converted to what? What happens with increase in this compound? | Acetyl-CoA increase beyond normal causes fatty acid synthesis fatty livers increase in VLDL |