Glands and the Digestive System
Several glands are involved in the digestion process. These include the salivary glands, glands in the stomach, and glands in the duodenum or small intestine.
The salivary glands located under the tongue, and in the back of the mouth, produce saliva in the mouth. Enzymes in the saliva provide the first stage of chemical digestion, helping breakdown fats and carbohydrates.
Glands in the stomach secrete gastrin that stimulates the stomach to produce gastric juices. These gastric juices help in the digestion of protein. The gastric juices also kill potentially harmful bacteria in the food.
Glands in the duodenum or small intestine secrete several hormones including secretin, cholecystokinin (CCK), and gastric inhibitory peptide (GIP). Secretin is secreted in response to acidic chyme from the stomach. Secretin stimulates the pancreas to produce sodium bicarbonate neutralizing the acid. CCK stimulates pancreatic enzymes that assist in the breakdown of fats, proteins, and carbohydrates. GIP decreases the stomach contractions, slowing the rate of food entering the duodenum, and giving the small intestine more time to digest the fats, proteins, and carbohydrates.