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Smali Intestine Motiiity

GASTROINTESTINAL PHYSIOLOGY

Rhythmic sepmentation

Intraluminal pressure slightly elevated

Figurę 7.19 Motility or the Smali Intestine-

Ihe smali intestine has two generał types of motility paitems. These motility patterns are under the control of the enteric nervous system tprimarily the myenteric plexus). The first pattem, segmentalion, serves to mix and churn the luminal contents. The second pattern, peristalsis. serves to move the luminal contents distally. In some instanees, reverse peristalsis occurs. as does a perisialtic rush. In the absence of food (interdigestive phase). there is a periodic wave (every t to 2 hours) of penstalsis that begins in the stornach and sweeps down the length nf the smali intestine. This wave is called the migrating motor (or myoclcctric) complex (MMC) and serves to doan the intestine and maintain a Iow bacterial counl in the smali intestine. The MMC is modulator! by motilin.

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