Title: The physiology and pathophysiology of constipation
Abstract: A definition of constipation based on a survey of a normal population is attempted. The mechanism of normal colonic motility and, in particular, its independent segmenting activity are stressed. Constipation is seen to result from any of a number of mechanisms including: (1) Inadequate bulk being presented to the distal colon. (2) Hyperactivity of the segmenting mechanisms. (3) Exhaustion of the colonic musculature. (4) Disturbance of the defaecation reflexes. In normal adults the most common causes are those relating to the overactivity of the segmenting movements of the distal colon but a small number of persons have a true atonic constipation. In paraplegic patients, particularly those with lesions of the lumbar sacral cord, there is not only disturbance of the defaecation reflexes but probably hypersegmentation as well.