In other lectures, I have described the histology
of organs in the oral cavity that have an
important role in the digestive system. And
I've also described the histological structure
of the esophagus and the stomach and their
important role in the digestive system.
In this lecture, you are going to learn about
the histology of the small intestine and the
large intestine. At the end of the lecture,
I'd like you to understand the components
of the wall of the small intestine and the large
intestine, and the components, particularly,
the mucosa that is specialized for the various
functions these two organs carry out.
I'm also going to introduce to you some components
of the diffuse neuroendocrine system, and
also components of the gut-associated lymphoid
tissues, and also the enteric nervous system.
The small intestine is specialized to actually
absorb all the products that are digested
or broken down in the lumen from the secretions
of enzymes from various parts of the body.
Those digestive products are then absorbed
across the wall of the small intestine and
carried to the liver in the portal vein. The
large intestine actually stores unwanted or
undigested products, and then finally eliminates
them as feces. In this organ, there is a lot
of water absorption. So the mucosa of the
large intestine is really specialized for
water absorption. Also, because the whole
gut tube, the lumen of the gut is exposed
to the exterior, it will contain various pathogens.
So, I just want to make sure that we explain
and you're aware of the function of the gut
in trying to combat those pathogens, identify
them, and alert the immune system.
Starting with the small intestine, I want