Which statement is incorrect?
A) Absorption of salt and water converts the colonic contents into fecal material.
B) Colonic bacteria digest cellulose for their own growth and reproduction.
C) When mass movements of the colon propel feces into the rectum, stimulation of the stretch receptors in the rectal wall reflexively causes contraction of the internal and external anal sphincters to prevent defecation from occurring until an opportune time.
D) No digestive enzymes are secreted by the colon.
E) Haustral contractions in the colon are a type of mixing motility.

Question

Quizplus · Accepted Answer

The statement is incorrect because the stimulation of stretch receptors in the rectal wall actually causes relaxation of the internal anal sphincter, not contraction, to facilitate defecation. The external anal sphincter is under voluntary control and can contract to delay defecation until an appropriate time.

Which Statement Is Incorrect