What structure in the digestive system is primarily involved in nutrient absorption?

The small intestine plays a crucial role in nutrient absorption within the digestive system. Its inner surface is lined with tiny, finger-like structures called villi, which significantly increase the surface area for absorption. The small intestine is divided into three parts: the duodenum, jejunum, and ileum, each contributing to the digestion and absorption of nutrients. As food passes through the small intestine, digestive enzymes break down carbohydrates, proteins, and fats, allowing for these nutrients to be absorbed into the bloodstream.

In contrast, the stomach primarily functions to break down food mechanically and chemically but is not the site where most nutrient absorption occurs. The large intestine is mostly involved in the absorption of water and electrolytes, and the gallbladder serves as a storage organ for bile, which aids in the digestion of fats but does not play a direct role in nutrient absorption.