Book Chapter

Neurophysiology of defecation

Ejerskov, Cecilie, Rittig, Charlotte Siggaard

2015

Overview

This chapter describes defecation patterns in childhood, the functional anatomy of colon, rectum and anus, colorectal motility, defecation and touches down on the neurotransmitter serotonin and the role of central centers in irritable bowel syndrome. When assessing neurophysiology of defecation, the regulatory mechanisms include endocrine and paracrine function and the enteric nervous system (ENS). Overall, neural control of colorectal motility is provided by the ENS; the intrinsic nervous system of the submucosal and myenteric plexus and their neurotransmitters such as serotonin and the extrinsic nervous system; sympathetic and parasympathetic system and extrinsic sensory innervations. Defecation is a complex process involving the ENS and smooth and striated muscles. As a mass colonic movement generates filling of the rectum, the defecation will proceed with the voluntary relaxation of the puborectal muscle, straightening of the anorectal angle, and relaxation of the external anal sphincter.

• Publisher: John Wiley & Sons, Ltd
• Subject: children / colon motility / constipation / defecation / enteric nerve system / irritable bowel syndrome / rectal motility / serotonin / the hypothalamic–pituitary–adrenal (HPA) axis
• ISBN: 9781118814796, 1118814797