Final answer:
Adynamic ileus involves the loss of intestinal peristalsis without mechanical obstruction. It can affect the normal functioning of the gastrocolic and gastroileal reflexes, leading to problems with food residue transfer from the ileum to the cecum and can have various underlying medical causes.
Step-by-step explanation:
The term adynamic ileus, or paralytic ileus, refers to a disruption of the normal propulsive ability of the gastrointestinal tract where there is an absence of peristalsis without an obstructive cause. This condition can be a complication of various medical and surgical conditions. It can lead to a cessation of propulsive movement in the colon, a phenomenon that is normally activated by the presence of food in the stomach, known as the gastrocolic reflex. The related gastroileal reflex is a long reflex that increases the strength of segmentation in the ileum, which is the final part of the small intestine. When functioning properly, increased motility in the ileum triggers the relaxation of the ileocecal valve, allowing digested food remnants to enter the cecum, the first part of the large intestine. Following the passage of chyme, the ileocecal sphincter closes to prevent backflow into the ileum. Disruptions in these reflexive movements or in the absorption functions of the ileum, such as in cases of parasitic infections or peritonitis, can lead to the development of an adynamic ileus.