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Old 04-11-2015
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Default Liver zones

hey everyone

regarding zone I and zone III of the liver, can anyone please explain why zone 1 is affected 1st by viral hepatitis and INGESTED toxins.

and why is zone III most sensitive to METABOLIC toxin (if anyone may comment on the specific differences of toxin in each zone, that would be great), finally why is it at this site that alcoholic hepatitis occurs?

thanks in advance.
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Old 04-11-2015
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Alcoholic hepatitis occurs in zone 3(pericentral vein) i'm not sure about WHY different zones are affected by different toxins but i think it has got to do with tye direction of blood flow which is from zone1 towards zone 3, so ingested toxins would come in contact with zone 1 first after being absorbed from the gut and travelling towards liver via portal vein. The p450 enzyme system is in zone3, so metabolic toxins would be metabolized there in zone 3 thus affecting that zone ! This is what i can think of based on logic.
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Old 04-11-2015
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The zone 3 is near the central vein right, where the blood from portal vein and hepatic artery got mixed right, so O2 tension near the zone 3 is lowest so Metabolic toxins might target an area where the O2 conc is least...O2 conc being really low might have something to do with this but I am not sure how.

Just a thought!

And as you might know NADH is needed by all catabolic reactions like glycolyis,krebs cycle etc where NADH is used as a currency for energy.

The cell already low on oxygen wont have those two NAD+ it needs to start glycolysis so will use alcohol metabolism instead to generate the NADH and live upon alcohol metabolism as a main source of energy, so the more alcohol the more energy but this also means production of acetaldehyde and acetate which is hepatotoxic and will lead to hepatitis

And here is a fact from Kaplan anatomy book(histology section),

Zone1 deals with glycogen synthesis and plasma protein synthesis
Zone3 deals with alcohol,lipid and drug metabolism

So like Hassan said Zone 3 deals with drugs so must be responsible from injuries due to metabolic toxins
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Last edited by CleverFOX; 04-11-2015 at 10:34 AM.
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