Defecation Reflex: Any reaction of the large bowels that stimuli various functions and that are involuntary is referred to as the defecation reflex. These are reflexes that are controlled by the autonomic nervous structure and they play a vital part in the process of defecation along with the somatic reflex located in the wall and which is the controlled portion of this function. The 2 major reflexes for defecation are the “parasympathetic defecation reflex” and the “intrinsic myenteric defection reflex”.
When the feces enter the rectum this causes expansion of the wall of the rectal area. This stretching stimulates indicators to the sigmoid and descending colons thru the network of nerves to intensify peristalsis. This nerve network is a portion of the nervous system that is known as enteric and is the gut’s internal network of reflexes.
The peristaltic contractions extend to the anus and rectum. Fecal material is motivated ever so closely to the anus as needed. When these contractions arrive at the anus, there it triggers the anal sphincter that is internal and that is always straitened, to relax itself. It happens by signals that are inhibitory thru the “myenteric plexus” to decrease constriction to the sphincter.
Defecation can happen at this time when there is relaxation of the anal sphincter externally. But, with no “parasympathetic defecation reflex”, a bowel movement is reliant solely on the reflex that is intrinsic and is extremely weak.
The “parasympathetic defecation reflex” and the “intrinsic myenteric defecation reflex” function identically but the latte includes fibers of nerves denoted as parasympathetic in the total nerves of the pelvic. This can trigger peristaltic motion in the sigmoid and descending colon and the rectal area. It as well causes the external sphincter to relax. The dissimilarity is that the “parasympathetic defecation reflex” increases this procedure and makes this reflex that is intrinsic have more power. If stimulated sufficiently, it can even stimulate the sigmoid colon to totally vacant all material in the rectum quickly.