Circular folds

Circular Folds

Circular folds, also known as plicae circulares (pronounced: plicae cir-cu-lar-es), are large valvular flaps protruding into the lumen of the small intestine. They are a part of the gastrointestinal tract and play a significant role in nutrient absorption.

Etymology

The term "circular folds" is derived from the Latin words 'plica', meaning 'fold', and 'circularis', meaning 'circular'. The term accurately describes the physical appearance of these structures, which are circular and folded.

Function

The primary function of the circular folds is to slow the passage of partially digested food along the intestines and to increase the surface area for absorption. They achieve this by causing the food to spiral, or rotate, through the intestine, rather than passing straight through.

Anatomy

Circular folds are permanent features in the walls of the small intestine. They are most numerous in the jejunum, the middle part of the small intestine, and are absent in the last part of the small intestine, the ileum. Each fold is covered with a mucous membrane, which is covered in tiny finger-like projections called villi.

Related Terms

Gastrointestinal tract: The gastrointestinal tract is the digestive tract from the mouth to the anus, including the stomach and intestines.
Jejunum: The jejunum is the middle section of the small intestine, between the duodenum and the ileum.
Ileum: The ileum is the final section of the small intestine.
Villi: Villi are small, finger-like projections that extend into the lumen of the small intestine.