What are the three major motor functions of the stomach?

Answer 1

The fist part of gastrointestinal tract is it acidifies ingested food to enhance protein digestion. It also secrete proteolytic enzymes (pepsin), and it also moves food into the small intestine as chyme. The only substances absorbed through the stomach are caffeine, alcohol and aspirin.

Answer 2

• It stores the food bolus we swallow. This allows us to eat a large number of food calories in a relatively short time and then digest it over a longer period. Without the stomach's storage capacity, we would need to eat very small amounts of food continuously throughout the day, because the small intestine digests food very slowly. Gastric bypass induces weight loss by reducing the size of the stomach, so that less food (and thus fewer calories) can be eaten. See Bariatric Surgery Guide.
• It breaks down large fat and protein molecules in food, so they can be absorbed in the small intestine. To do this, the stomach releases a number of powerful gastric juicescontaining hydrochloric acid and other digestive enzymes. In addition to breaking down food, these acidic juices (PH 1-3) also kill bacteria in the food. For easier digestion, powerful muscles in the stomach wall churn the food into a paste of porridge-like consistency, called chyme. This churning action also ensures that the secreted gastric acids and enzymes are thoroughly mixed with the food.
• It empties the partially digested chyme into the duodenum (the first segment of the small intestine) at a manageable speed, through the the pyloric sphincter. While the intestine is full and still digesting food, the stomach acts as storage area for food.