Describe the two positive feedback loops involved in the defecation reflex

Question

What will be an ideal response?

Answer 1

The two positive feedback loops in the defecation reflex are (1 ) the short intrinsic myenteric defecation reflex, whereby stretch receptors in the rectal walls promote a series of peristaltic contractions in the sigmoid colon and rectum, moving feces toward the anus; and (2 ) the long parasympathetic defecation reflex, whereby parasympathetic motor neurons in the sacral spinal cord, also activated by stretch receptors, stimulate mass movements that push feces toward the rectum from the descending colon and sigmoid colon. Defecation occurs with the voluntary relaxation of the external anal sphincter.