What are the three folds of the small intestine called? What is their purpose?

Verified step by step guidance

1. Identify the three folds of the small intestine: plicae circulares, villi, and microvilli.
2. Understand that the plicae circulares are large, circular folds of the mucosa and submucosa that increase the surface area for absorption.
3. Recognize that the villi are small, finger-like projections that cover the plicae circulares, further increasing the surface area and containing blood vessels and lacteals for nutrient absorption.
4. Learn that the microvilli are tiny, hair-like structures on the surface of the epithelial cells of the villi, forming the brush border and significantly enhancing the absorptive capacity.
5. Comprehend that the primary purpose of these folds is to maximize the surface area for nutrient absorption, facilitating efficient digestion and absorption of nutrients in the small intestine.

Key Concepts

Duodenum

The duodenum is the first section of the small intestine, measuring about 25-30 centimeters long. It plays a crucial role in digestion by receiving chyme from the stomach and mixing it with bile from the liver and pancreatic juices. This combination helps to neutralize stomach acid and further break down food, allowing for nutrient absorption.

Jejunum

The jejunum is the middle section of the small intestine, approximately 2.5 meters long. Its primary function is the absorption of nutrients, including carbohydrates, proteins, and fats. The jejunum has a highly folded inner surface, which increases its surface area and enhances its ability to absorb nutrients effectively.

Ileum

The ileum is the final section of the small intestine, about 3-4 meters long. It is primarily responsible for the absorption of vitamin B12 and bile salts, as well as any remaining nutrients not absorbed by the jejunum. The ileum connects to the large intestine at the ileocecal valve, regulating the flow of material into the colon.