Human Physiology

Lesson 21 : Absorption,Metabolism,Excretion&Glands

Excretion of Undigested Food

Act of expulsion of feces through anus is termed as defecation and this process is complete as a result of a reflex action mediated through spinal cord, brain and nerves. Defecation is mixed reaction of body involving voluntary and involuntary actions. Time of defecation is decided by pressure exerted by feces on the rectal wall and anal sphincters. In young ones, the defecation reflex is poorly developed, thus they have little control over time of defecation. In adults, the reflex is highly developed and exerts substantial control over the time of defecation.