Circular folds

Circular folds (also known as plicae circulares) are large valvular flaps protruding into the lumen of the small intestine. The circular folds, along with the villi and microvilli, increase the surface area of the intestines and promote the absorption of nutrients.

Anatomy

The circular folds are not present in the stomach or the lowest part of the duodenum, but they are present for the rest of the small intestine, becoming larger and closer together as they progress down the ileum. They are permanent features in the walls of these organs, meaning they do not disappear when the intestines are empty.

Function

The primary function of the circular folds is to slow the passage of the partially digested food along the intestines, thus providing more time for absorption. This is achieved by the fact that they are not just simple protrusions, but rather they form spirals, which causes the chyme to spiral rather than move in a straight line down the intestines. This spiral movement promotes more efficient absorption by exposing the chyme to a greater surface area.

Clinical significance

In certain diseases, such as celiac disease, the circular folds, villi, and microvilli are damaged, leading to malabsorption of nutrients. This can lead to a variety of health problems, including malnutrition, anemia, and osteoporosis.

See also

• Small intestine
• Villi
• Microvilli
• Celiac disease

References

Circular folds Resources
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