What organ is primarily responsible for nutrient absorption?

The small intestine plays a crucial role in the digestive system and is primarily responsible for nutrient absorption. It has a large surface area due to the presence of villi and microvilli, which significantly increase the amount of nutrients that can be absorbed into the bloodstream. The small intestine contains three parts: the duodenum, jejunum, and ileum. While the duodenum is involved in the initial digestion of food with enzymes and bile, the jejunum and ileum are where most nutrient absorption occurs.

In contrast, the stomach's primary function is to break down food through mechanical and chemical processes, but it does not absorb significant nutrients. The large intestine mainly absorbs water and electrolytes, with minimal nutrient absorption taking place. The liver, although essential for processing nutrients and detoxifying substances, is not involved directly in the absorption process itself. Thus, the small intestine stands out as the key organ for nutrient absorption in the digestive tract.