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What are the 2 metabolic pathways for metabolizing ethanol?
- Major pathway = alcohol dehydrogenase in cytosol- Reaction reduces NAD to NADH + H+
- Alternate pathway = microsomal ethanol oxidizing system (MEOS) in smooth endoplasmic reticulum
- - Chronic alcoholics
- - Part of cytochrome P-450 enzyme system
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How would ratio of NAD/NADH be affected by alcohol dehydrogenase pathway? (p.40)
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Understand connection between alcohol intoxication and/or chronic alcoholism to following disturbances: fatty liver, hyperlipidemia, hypoglycemia, hyperlacticacidemia, and cirrhosis. (p.40)
- Fatty liver - oxidation of fatty acids --> increased cholesterol, fatty acids, TG formation --> accumulation of fat in liver
- Hyperlipidemia - because protein synthesis usually not involved, increased TG and cholesterol synthesis --> increased synthesis of VLDL --> hyperlipidemia
- Hypoglycemia - NAD+ necessary for gluconeogenesis; decreased NAD+ --> decreased gluconeogenesis --> decreased blood glucose
- Hyperlacticacidemia - Low NAD --> inhibition of TCA --> increased lactate --> lactic acidosis
- Cirrhosis - ETOH = fatty liver = hyperlipidemia = hypoglycemia = hyperlacticacidemia = cirrhosis
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What is the relationship between protein breakdown and ammonia formation?
- Protein breakdown via deamination
- Ammonia released during deamination process
- Ammonia removed from bloodstream by liver --> urea – excreted by kidneys
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How is ammonia normally detoxified by the body?
Liver turns ammonia into urea by combining ammonia with CO2.
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What would be the potential consequence of toxic levels of ammonia on the brain?
- Encephalopathy
- Irritability
- Confusion
- Coma
- Death
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Define cirrhosis.
- Term for chronic end-stage liver disease
- Chronic irreversible disease of liver in which normal architecture of entire liver destroyed by connective tissue and regenerative nodules
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Clinical manifestations of cirrhosis.
- Decreased urea synthesis --> increased blood ammonia --> hepatic encephalopathy
- Decreased clotting factors (V, VII, IX, X), fibrinogen, and prothrombin --> hemorrhage
- Decreased albumin --> ascites
- Decreased hormone detoxification --> increased circulating estrogen --> gynecomastia, testicular atrophy, hair loss
- Altered liver structure --> decreased blood circulation through liver --> shunting --> undetoxified blood --> increased blood ammonia --> hepatic coma
- Portal hypertension --> varices, splenomegaly
- Impaired bile circulation --> jaundice
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In hepatic cirrhosis, why is hypoalbuminemia associated with ascites? (p.42)
- Albumin = large protein produced in the liver
- One of main proteins involved in oncotic pressure of vascular system
- Oncotic pressure keeps water in vascular space
- No albumin --> decreased oncotic pressure
- Water shifts into interstitial spaces and cavities – peritoneal cavity
- Decreased albumin synthesis --> loss of vascular volume --> ascites
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