IAH AC Gastrointestinal Disease

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liver
blood
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receptor for e.g.
corticotrophic hormone
immune system
tight junction
3
food particles
bacteria
gut lumen
1. 2
mucous and
unstirred water layer
the intestinal barriers
© IAH 2007
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The intestinal tract and the liver comprise of 5 barriers which will keep undesired
particles out of the body.
These are:
1. The mucous and water layer covering the mucosa on the luminal side
2. The symbiotic bacteria, which through their numbers form a passive barrier on
the luminal side, so that toxins do not come into contact with the gut lining, but
also will use certain toxins in their metabolism, and therefore will render them
harmless before they even come into contact with the mucosa.
3. The tight junction. This is the most important barrier, and is not an anatomical
barrier, but rather a channel, which closed integrity is kept up by active action
of the adjacent mucocytes. This means that the cells need energy and fuel to
be able to keep up this physiological function. Should the energy in the
epithelial cell fall, or there are not enough nutrients, this barrier will be
impaired. Infections, stress and toxins, like alcohol can all affect this important
function.
4. The gut immune system or GALT form the 4th barrier (see later)
5. The liver is the last barrier, as all the blood from the gut drains to the liver via
the portal vein, and toxins can be finally metabolised and made harmless
here, or made water soluble for excretion.
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