What does the small intestine primarily do?

The primary function of the small intestine is to absorb nutrients into the bloodstream. This process occurs after food is broken down by digestive enzymes and mixed with bile. The walls of the small intestine are lined with tiny, finger-like projections called villi, which significantly increase the surface area available for absorption. Through these structures, carbohydrates, proteins, fats, vitamins, and minerals are effectively absorbed into the bloodstream and transported to the cells of the body for energy, growth, and repair. This nutrient absorption is crucial for maintaining overall health, providing the body with the essential components necessary for various bodily functions.

While digestive enzymes are involved in the breakdown of food, the actual absorption of nutrients is the most critical role of the small intestine. Other options, such as storage of waste material or regulation of hydration levels, are functions carried out by different parts of the digestive system and the body. The large intestine, for example, is primarily responsible for storing waste and absorbing some water, whereas hydration regulation is generally managed by the kidneys and endocrine system.