KEY POINTS

1. Slow waves of electrical depolarization are a unique feature of gut smooth muscle.

2. When slow waves reach sensitized smooth muscle cells, action potentials and contraction result.

3. Coordinated motility enables the lips, tongue, mouth, and pharynx to grasp food and propel it down the gastrointestinal tract.

4. Motility of the esophagus propels food from the pharynx to the stomach.

5. The function of the stomach is to process food into a fluid consistency and release it into the intestine at a controlled rate.

6. The proximal stomach stores food awaiting further gastric processing in the distal stomach.

7. The distal stomach grinds and sifts food entering the small intestine.

8. Control of gastric motility differs in the proximal and distal stomach.

9. The rate of gastric emptying must match the small intestine's rate of digestion and absorption.

10. Between meals, the stomach is cleared of indigestible material.

11. Vomiting is a complex reflex coordinated from the brainstem.

12. Motility of the small intestine has digestive and interdigestive phases.

13. The ileocecal sphincter prevents movement of colon contents back into the ileum.

14. Motility of the colon causes mixing, retropulsion, and propulsion of ingesta.

15. The colon is an important site of storage and absorption in all animals.

16. Despite large anatomical differences in the colons of herbivores compared to omnivores and carnivores, there are similarities in motility.

17. The anal sphincter has two layers with separate innervation.

18. The rectosphincteric reflex is important in defecation.

19. Major differences between avian and mammalian digestive systems include, in birds, both the lack of teeth and the separation of gastric functions into distinct anatomical regions.