Nouns used in singular and plural. Which phrase is correct - the class was or the class were? Is the word class a singular noun or a plural noun? This question cannot be answered with Yes or No. Use the singular if you see the class as a group of students. Use the plural if you see the class as single students. In British English the plural is used more often than in American English. There are more words which can be singular or plural nouns: army.
In much of a digestive tract such as the human gastrointestinal tract, smooth muscle tissue contracts in sequence to produce a peristaltic wave, which propels a ball of food (called a bolus while in the esophagus and upper gastrointestinal tract and chyme in the stomach) along the tract. The primary peristaltic wave forces the bolus down the esophagus and into the stomach in a wave lasting about 8â9 seconds. 2  The wave travels down to the stomach even if the bolus of food descends at a greater rate than the wave itself, and continues even if for some reason the bolus gets stuck further up the esophagus.
Peristalsis. a wavelike contraction that propels the contents of tubular organs, for example, the intestine, stomach, and ureters, caudally in animals or in a downward direction in man.Peristalsis is the result of many coordinated contractions of the longitudinal and transverse muscles in the walls of a tubular organ.A single peristaltic wave takes the form of a circular constriction around the lumen that moves along the length of the organ.eristalsis is the result of many coordinated contractions of the longitudinal and transverse muscles in the walls of a tubular organ. A single peristaltic wave takes the form of a circular constriction around the lumen that moves along the length of the organ.