Final answer:
The main function of the stomach is mechanical digestion, which involves the breakdown and churning of food. This prepares the consumed food for further digestion and absorption, primarily in the small intestine.
Step-by-step explanation:
The major process or function that occurs in the stomach is mechanical digestion. While the stomach does participate in chemical digestion by breaking down proteins and fats into smaller molecules, the primary activity it is known for is the churning and breakdown of food particles. This prepares the food for further digestion and absorption in the small intestine.
Other processes that occur in the alimentary canal include propulsion, which is the movement of food along the digestive tract, and absorption, which is the uptake of nutrients into the body, primarily occurring in the small intestine. Defecation is the elimination of waste from the body, while deglutition is the act of swallowing, and ingestion is the intake of food through the mouth; these do not primarily occur within the stomach.