The chyme, or partially digested food from the stomach, is pushed along the small intestine by muscle contractions called peristaltic waves. Most of the chemical digestion and breakdown of the food happens in the duodenum. Food is mixed with bile from the gallbladder and digestive juices from the pancreas.he digested food passes into the capillaries and lymphatic vessels in the wall of the intestine. Nutrients such as glucose and amino acids are absorbed into capillaries, while fats are absorbed into the lymph vessels. The ileum is the last section of the small intestine. It mainly absorbs vitamin B12 and bile salts.