bluestar
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I listened to Goljan's audio today and got confused on this topic. I try to summerize what I understand here, please correct or add accordingly:
zone 1, peri-portal-triad zone,
zone2, intermediate zone, damaged in yellow fever
zone3, pericentral vein zone, get least blood supply. fatty changes and most suseptible to ichemia damage.
I don't understand which zone gets injured most often in general? Is it central vein zone cuz it gets least blood supply? If so, then at what circumstances can peri-portal-triad zone gets injured?
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| Ahab
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It depends on the nature of the damaging agent.
The periportal area is the most susceptible to toxic injury as the toxins ingested by the body are at their highest concentration here as they have not yet been metabolised.
Not sure about the thing about yellow fever, from my understanding viral damage to liver cells was relatively indiscriminate, thus on microscopy you see piecemeal necrosis of individual liver cells.
The pericentral zone is most susceptible to ischaemic injury for two reasons.
1. Blood supply to liver is mixed venous/arterial and at a lower O2 conc to begin with, blood flows from periportal to central vein therefore most of the oxygen is taken by zone 1 cells. By the time blood reaches Zone 3 there is not too much O2 left even in ideal circumstances.
2. In congestive heart failure venous blood gets backed up in the circuitry, particularly in the pericentral region increasing venous pressure hindering the flow of oxygenated blood to the region causing ischaemia like a dam
At least thats how I view it
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| namf
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Bluestar--in goljan, I wondered along with you at this topic. My initial reasoning was such that since the toxic substances hit the periportal-triad zone 1st, it would have the greatest damage. Howevere, on further thought--and Goljan saying so--I could see the idea that the peri-central vein zone (the same central vein that leads to the portal vein and then to the IVC) would be the most oxygen depleted and this would make it most succeptible to injury.
I threw my hands up and just shrugged when I think at one point goljan did say that CCl4 (dry cleaning industry chemical) often leads to periportal-triad injury..I would have thought that it would have the same peri-central damage as Aspirin (or was that acetominophen/Tylenol!!??)
Hope this helps.
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| mani
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i agree with ahab
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| bluestar
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thank you guys for replying! Could you name some damage/disease specific to each zone?
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