The beginning portion is where the digestion actually takes place. This is known as our duke. So within our duodenum, we basically have the breakdown of the macromolecules into our amino acids, the fatty acids, and into our monosaccharides. 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.