Tag: endocrine system and chemical co-ordination

Hormones are the chemicals which transfer signal from one part to the other. There are several hormones which have an effect on the stomach, pancreas as well as liver, these hormones are as follows:

Cholecystokinin is a peptide hormone of the gastrointestinal system, responsible for stimulating the digestion of fat and protein. Cholecystokinin, previously called pancreozymin, is secreted in the duodenum and causes the release of digestive enzymes and bile from the pancreas and gallbladder, respectively. 

The secretion of pancreatic juice is stimulated by secretin and CCK, produced by endocrine cells in the walls of the duodenum. The presence in the duodenum of acid material from the stomach stimulates the production of these hormones.

Cholecystokinin, previously called pancreozymin, is synthesized by I-cells in the mucosal epithelium of the small intestine and secreted in the duodenum, and causes the release of digestive enzymes and bile from the pancreas and gallbladder, respectively. 

Contraction of the muscle wall in the gallbladder is stimulated by the vagus nerve of the parasympathetic system and by the hormone cholecystokinin, which is produced in the upper portions of the intestine. The contractions result in the discharge of bile through the bile duct into the duodenum of the small intestine. 

Enterogastrone is a hormone, whereas amylase, trypsin and enterokinase are enzymes. Amylase is starch splitting enzyme, while trypsin is a proteolytic enzyme. Enterokinase is a proteolytic enzyme, which acts on trypsinogen and converts it to active trypsin. Enterogastrone, is a hormone secreted by the duodenal mucosa, when fatty food is in the stomach or small intestine; it is also thought to be released, when sugars and proteins are in the intestine. Enterogastrone is transported by the bloodstream to the glands and muscles of the stomach, where it inhibits gastric movements and secretions, possibly by blocking the production or activity of gastrin, the hormone that initially causes these functions.

Secretin is the most important hormone of digestive tract and also first hormone discovered in digestive tract. This hormone stimulates pancreas for synthesis and secretion of non enzymatic part of pancreatic juice. It also stimulates liver for secretion of bile juice and inhibit the gastric acid secretion in stomach and reduce rate of contraction of stomach.

As food enters the confined space of the stomach, it starts applying pressure to the stomach wall. As food enters the stomach, the food bangs against the stomach wall, distending it. This distention causes the stomach to release gastrin. Gastrin stimulates the gastric glands to secrete more gastric juice.