Which area of the digestive system is directly involved in nutrient absorption?

The small intestine is the primary site for nutrient absorption in the digestive system. It is structured to maximize its surface area, featuring numerous folds, villi, and microvilli, which increase the contact area between the intestinal contents and the absorptive cells. The small intestine has three sections: the duodenum, jejunum, and ileum, where various nutrients such as carbohydrates, proteins, fats, vitamins, and minerals are absorbed into the bloodstream.

The stomach, while critical for the initial breakdown of food and enzyme activity, does not absorb nutrients effectively. Its role is primarily to digest food into a semi-liquid form, known as chyme, before it moves into the small intestine. The large intestine's main function involves water and electrolyte absorption, along with the formation of feces, rather than the absorption of nutrients. The esophagus primarily serves as a conduit for food traveling from the mouth to the stomach and does not play a role in nutrient absorption.