Now, in the middle portion, known as our geunum, and our end portion, known as the ilium, this is where we absorb those nutrients. So the intestinal cells of the jugunum and our ilium, known as in terrace, basically absorb those individual nutrients into the cells and then transport those nutrients into the blood system and our lymph system, as we'll see in just a moment. So let's describe what the actual structure is inside the small intestine. And let's take a cross section of the small intestine. We basically get the following diagram. Now, the outer portion, shown in red, is the thick and a thin layer of smooth muscle which is controlled by the autonomic nervous system.