Other Autonomic Reflexes Affecting Bowel Activity

OTHER AUTONOMIC REFLEXES AFFECTING BOWEL ACTIVITY 

The peritoneo-intestinal reflex is very much like the intestino-intestinal reflex, except that it results from irritation of the peritoneum it causes intestinal paralysis. The reno-intestinal and vesico-intestinal reflexes inhibit intestinal activity as a result of kidney or bladder irritation. Finally, the somato-intestinal reflex causes intestinal inhibition when the skin over the abdomen is irritatingly stimulated (Guyton, 1981). 

Constipation is a complaint commonly seen in clinical practice. Because of the wide range of normal bowel habits, constipation is difficult to define precisely. Most persons have at least three bowel movements per week, and constipation has been commonly defined as a frequency of defecation of less than three times per week. However, stool frequency alone is not a sufficient criterion to use because many constipated patients describe a normal frequency of defecation but subjective complaints of excessive straining, hard stools, lower abdominal fullness, and a sense of incomplete evacuation. Thus, a combination of objective and subjective criteria must be used to define constipation. 

Pathophysiologically, constipation generally results from disordered colonic transit or anorectal function as a result of a primary motility disturbance, certain drugs, or in association with a large number of systemic diseases that affect the gastrointestinal tract. Constipation from any cause may be exacerbated by chronic illnesses that lead to physical or mental impairment and result in inactivity or physical immobility. Additional contributing factors may include a lack of fiber in the diet, generalized muscle weakness, and possibly stress and anxiety. 

In the patient presenting with a recent onset of constipation, an obstructing lesion of the colon should be sought. In addition to a colonic neoplasm, other causes of colonic obstruction include strictures due to colonic ischemia, diverticular disease, or inflammatory bowel disease foreign bodies or anal strictures. Anal sphincter spasm due to painful hemorrhoids or fissures also may inhibit the desire to evacuate. 

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OTHER AUTONOMIC REFLEXES AFFECTING BOWEL ACTIVITY... 

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