Final answer:
The small intestine, with the aid of pancreatic enzymes and bile, is responsible for most of the chemical digestion of food in the gut.
Step-by-step explanation:
The small intestine is primarily responsible for the chemical breakdown of food within the gastrointestinal (GI) system. It achieves this through a combination of digestive enzymes from the pancreas and the intestinal brush border, as well as bile, which aids in the emulsification and digestion of fats. These enzymes break down complex food molecules into simpler ones, such as proteins into amino acids, carbohydrates into simple sugars, and fats into fatty acids and glycerol, to be absorbed by the body.
In the mouth, the process begins with the salivary glands releasing amylase, an enzyme that starts the digestion of carbohydrates. The tongue and teeth contribute to the mechanical digestion, turning food into a bolus for easier swallowing. After passing through the pharynx and esophagus via peristalsis, the food reaches the stomach, where gastric enzymes and acid further break down protein in the food.
In summary, the small intestine, along with the enzymes from the pancreas and bile from the liver, play critical roles in the chemical digestion of food within the GI system.