Q: During what in the small intestine do rings of smooth muscle repeatedly contract and then relax?


Read this paragraph and choose the correct option from the provided answers:

Mechanical Digestion in the Small Intestine The movement of intestinal smooth muscles includes both segmentation and a form of peristalsis called migrating motility complexes. The kind of peristaltic mixing waves seen in the stomach are not observed here. If you could see into the small intestine when it was going through segmentation, it would look as if the contents were being shoved incrementally back and forth, as the rings of smooth muscle repeatedly contract and then relax. Segmentation in the small intestine does not force chyme through the tract. Instead, it combines the chyme with digestive juices and pushes food particles against the mucosa to be absorbed. The duodenum is where the most rapid segmentation occurs, at a rate of about 12 times per minute. In the ileum, segmentations are only about eight times per minute (Figure 23.20).

 Choices:

- mitosis

- contraction

- compression

- segmentation


A:
segmentation