The small intestine is a tubular structure within the abdominal cavity that carries the food in continuation with the stomach up to the colon from where ... These are called the plicae circulares.

Light micrograph of a section through the wall of the human jejunum, part of the small intestine. The lining has many folds, known as plicae circulares or Kerckring's valves, in this region.

The small intestine can measure about 9–16 ft, while the large intestine is roughly 5 ft long. The intestines have the important role of helping break down and absorb nutrients from food and drink.