The organ primarily responsible for processing nutrients is the small intestine. This tube-like structure is part of the digestive system, where most of the digestion and absorption of nutrients occurs. The small intestine has three segments—duodenum, jejunum, and ileum—each playing a role in breaking down food and absorbing nutrients, such as carbohydrates, proteins, and fats. The absorbed nutrients then enter the bloodstream through the intestinal walls and are transported to various parts of the body to be used for energy, growth, and repair.