List the hormones secreted by G-I tract.

Hint: The tract which starts from the mouth and end to the anus is called the Gastrointestinal tract. The organs which include in the GI tract are the digestive system in humans and other animals. For example – small intestine, liver, stomach, esophagus, etc. The main function of the GI tract is digestion and absorption of nutrients that are ingested and also waste product excretion during digestion.

Complete answer:
The gastrointestinal tract includes both the stomach and small intestine and produces hormones like:
Gastrin is the hormone secreted by the stomach from the ‘G’ cells. The different stimuli produced by the gastrin hormone includes meal ingestion, stomach distention, and products of protein digestion. The major function of gastrin hormone is the stimulation of secretion of gastric acid and gastric mucosa growth.
There are 4 hormones secreted by the small intestine which are named cholecystokinin, secretin, gastric inhibitory peptide (GIP), and motilin.

The functions of different hormones secreted by the small intestine are:
- Cholecystokinin: The major function of this hormone is in the process of digestion and appetite. The pancreatic enzyme and bicarbonate secretion along with the gallbladder contraction are stimulated by the cholecystokinin hormone. The exocrine pancreas growth stimulates this hormone and also inhibits the emptying of the gastric (food entry into the intestine by stomach emptying).
- Secretin: The secretion of pepsin from the stomach and bicarbonate from the pancreas and gallbladder both is stimulated by the secretin hormone. The growth of the exocrine pancreas is promoted by this hormone and also inhibits the secretion of gastric acid.
- Gastric inhibitory peptide (GIP): This hormone stimulates the insulin release from the pancreas and inhibits the secretion of gastric acid.
- Motilin: This hormone enables the gastrointestinal tract motility.

Note: The gastrointestinal tract is the major and longest part of the human body. There are various organs that come under it and perform various functions. The hormones released or secrete by the GI tract mainly perform digestion activities. The ingested food absorption and waste product removal from the body is also performed by the GI tract.