Question

What is peristalsis? What is its role in digestion?

Answer 1

Hint: A progressive wave of contraction and relaxation of the tubular muscular system, in particular alimentary canal, through which the contents are pushed in an anterograde direction through the system.

Complete answer: Peristalsis is a series of wave-like muscular contractions that moves food to different processing stations in the digestive tract.

When a bolus of food is swallowed, the peristaltic process starts in the oesophagus. The smooth muscle's strong wave-like motions bring the food to the stomach in the oesophagus, where it is churned into a fluid mixture called chyme.

In addition, it begins in the small intestine where it combines and transfers the chyme back and forth, allowing nutrients to be absorbed through the walls of the small intestine into the bloodstream.

In the large intestine, peristalsis ends where water is drained from the undigested food material into the bloodstream. Eventually, the residual waste products are eliminated from the body through the rectum and the anus.

Role of peristalsis in digestion takes place when the food is swallowed and transferred via the oesophagus after food is chewed into a bolus. To prevent it from being squeezed back into the mouth, smooth muscles contract behind the bolus. Rhythmic, unidirectional waves of contractions then work to drive the food into the stomach rapidly. The migration motor complex (MMC) allows peristaltic waves to be activated. The procedure only works in one direction and moves food from the mouth into the stomach is its sole esophageal feature (the MMC also works to clear the remaining food into the small intestine in the stomach and the remaining particles into the colon in the small intestine).

Note: Bayliss and Starling first defined Peristalsis as a form of motility in which there is contraction above and stimulating relaxation below a section. Peristalsis does not affect vagotomy or sympathectomy to some degree, suggesting its mediation by the local, intrinsic nervous system of the intestine.