What is the term for the involuntary muscular contractions that propel solid and semisolid materials through the alimentary canal?

Peristalsis is the term for the involuntary muscular contractions that propel solid and semisolid materials through the alimentary canal.

Explanation:

Peristalsis is a wave-like muscle contraction due to the involuntary movements of the longitudinal and circular muscles in the alimentary canal (digestive tract).  It also occurs in other hollow tubes of the body such as the urinary tract. In the digestive tract, it begins at the upper portion of the esophagus and also occurs in the stomach and intestines.  

When food is swallowed, the peristaltic waves push the food down the esophagus into the stomach. The muscles in the stomach continue the peristalsis and the food moves through the digestive tract, where it is further digested and broken down with the help of digestive juices present in the stomach and small intestine. The peristalsis is continued by the muscles of small intestines, where the nutrients in the digested food are absorbed into the bloodstream. The movement of bile from the gallbladder into the duodenum of the small intestine also occurs via peristalsis. The undigested food is then passed to the large intestine, where the peristalsis continues and it is eliminated through the anus as feces after the reabsorption of water and some minerals.  

When peristalsis does not occur, it may cause disorders such as dysphagia (difficulty in swallowing foods and liquids), irritable bowel syndrome (diarrhea or constipation), esophageal spasms, gastroparesis (muscles of the stomach not moving food into the small intestine) and GERD (Gastroesophageal reflux disease).

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