Processes Flashcards
1
Q
Defecation
A
- Process is triggered when content enters the sigmoidal colon and mechanoreceptors are activated by stretch
- Distension in the rectum will activate local sensory pathways leading to relaxation of the internal anal sphincter which is under both enteric and autonomic control, external anal sphincter will remain contracted
- When the CNS decides it is okay to go, the sacral nerve will stop excitatory input to the external anal sphincter promoting relaxation and allowing content to move through
- Clenching of the abdominal muscles will increase abdominal pressure pelvic floor relaxation widens anorectal angle to facilitate fecal expulsion
- Decision to resist the urge to defecate is acompanies by relaxation of CM resulting in increased rectal volume, reduced intrarectal pressure, drop in muscle tension and removal of the stimulus for mechano receptors