glial cells, supportive cells. The small intestine
has three different components,
and they're indicated on this slide. On the
left-hand side is the duodenum. The duodenum
is characterized by having submucosal glands,
mucous secreting glands, particularly near
the entrance from the pylorus component of the
stomach where acidic chyme could be entering
into the duodenum. These mucus-secreting glands
try to neutralize any of that acid. And these
submucosal glands will become very limited as
you progress along the length of the duodenum.
The jejunum has uncharacteristic features,
but really, the only difference between the
duodenum and later the ileum is the fact that
these have very long villi, but they don't
have submucosal glands, and they don't have
Peyer's patches as the ileum has.
Peyer's patches are areas that give an indication
that there has been an immune response occurring
in response to the invasion and identification
of a pathogen. So, using these criteria, you
can see or at least identify and distinguish
the duodenum from the jejunum and the ileum.
And they are the three main components as
I mentioned before of the small intestine.
These two sections show examples of the gut-associated
lymphatic tissue. There's also a similar
lymphatic tissue in bronchi of the lung, the
bronchi-associated lymphatic tissue. And sometimes
we see this lymphatic tissue underneath other
mucosal surfaces. So we call them mucosa-associated
lymphatic tissue. But as I said previously,
they're evidence of an immune response.