Small intestine

A vital organ responsible for the majority of nutrient absorption and digestion in the body.

The small intestine is a long, coiled tube that is part of the digestive system, connecting the stomach to the large intestine. It is divided into three primary sections: the duodenum, jejunum, and ileum. Measuring approximately 6 to 7 meters in length, it plays a central role in breaking down food and absorbing nutrients.

Terminologia Anatomica

intestinum tenue

System

Digestive system

Function

The primary function of the small intestine is to complete the digestive process and absorb nutrients from the food. The small intestine achieves this through a combination of enzymatic action and a large surface area provided by tiny finger-like projections called villi and microvilli. In the duodenum, the first section, enzymes from the pancreas and bile from the liver aid in the breakdown of carbohydrates, proteins, and fats. The jejunum, the middle section, is primarily responsible for the absorption of nutrients, while the ileum, the final section, absorbs any remaining nutrients and bile salts. The absorbed nutrients then enter the bloodstream, providing essential substances for the body's various functions.

Location

The small intestine is located in the central and lower abdominal cavity, extending from the pyloric sphincter of the stomach to the cecum of the large intestine. It is typically situated between the stomach, which lies above it, and the large intestine, which encircles it in an inverted 'U' shape. The small intestine is well-positioned to receive digestive juices from the pancreas and bile from the liver, further enhancing its role in digestion and absorption. Its extensive length allows it to have a significant surface area, which is crucial for the effective absorption of nutrients.

Did You Know?

The small intestine can grow to be around 6 to 7 meters in length in adults, making it one of the longest organs in the human body.
In addition to nutrient absorption, the small intestine also plays a role in immune function by housing a significant amount of lymphoid tissue.
The surface area of the small intestine is roughly equivalent to the size of a tennis court, thanks to its many folds, villi, and microvilli.