What stimulus initiates the defecation reflex?
A)release of secretin and cholecystokinin (CCK)by the small intestine
B)the stretch of the rectum
C)pressure on the gastroesophageal sphincter
D)presence of acid in the stomach

Question

Quizplus · Accepted Answer

The stretch of the rectum initiates the defecation reflex, which triggers the relaxation of the internal anal sphincter and contraction of the rectal muscles to expel feces. Secretin and CCK are released in response to the presence of food in the small intestine and stimulate pancreatic enzyme secretion and bile release, respectively. Pressure on the gastroesophageal sphincter would not initiate the defecation reflex. The presence of acid in the stomach would stimulate the release of gastrin, which promotes gastric acid secretion.

What Stimulus Initiates the Defecation Reflex