Which structure is primarily responsible for the absorption of nutrients in the digestive system?

The small intestine is primarily responsible for the absorption of nutrients in the digestive system. It is a long, coiled tube where most of the digestion and absorption of food occurs. This structure consists of three parts: the duodenum, jejunum, and ileum.

In the small intestine, the presence of villi and microvilli greatly increases the surface area available for absorption. These tiny, finger-like projections allow for a more efficient uptake of essential nutrients such as vitamins, minerals, carbohydrates, proteins, and fats into the bloodstream. The wall of the small intestine also has specialized cells that facilitate the transport of these nutrients.

While the stomach plays a critical role in breaking down food, its primary function is not nutrient absorption. The large intestine is mainly involved in the absorption of water and salts and prepares waste for elimination. The liver is crucial for processing nutrients and metabolic functions but does not directly absorb nutrients from the digestive tract. Therefore, the small intestine stands out as the key site for nutrient absorption within the digestive system.