Question

Is Gastrin a hormone?

Answer 1

Hint: Hormones are chemicals that act like messenger molecules in the body. After they are produced in one part of the body, they reach other parts of the body via the bloodstream. They help in controlling and coordinating how cells and organs perform their work.

Complete answer:
Gastrin is a peptide hormone majorly functioning by increasing gastric mucosal development, gastric motility, and secretion of hydrochloric acid inside the stomach. It is located in G cells of the gastric antrum and duodenum. Gastrin is basically secreted in order to respond to vagal and gastrin-releasing peptide (GRP) stimulation right after the intake of peptides, amino acids, gastric expansion, and an increased stomach pH. Gastrin release is lowered in response to paracrine inhibition via somatostatin and reduced stomach pH.
Gastrin is released into the bloodstream and transported to the gastric fundus and cardiac region of the stomach, where most HCl -secretion parietal cells are located. HCl is essential for the transformation of inactive pepsinogen into active pepsin, which helps in digestion of proteins in the stomach.
G-cells release gastrin into the systemic circulation, which permits the transportation of gastrin to parietal cells and enterochromaffin-like (ECL) cells in the gastric fundus. Gastrin revives the proliferation of gastric mucosal endocrine cells i.e., parietal cells, ECL cells, etc. This character of gastrin may be associated with the initiation of some cancers. Gastrin has also been found to interact with acinar cells of the pancreas, gastric smooth muscle cells, endocrine cells, and some white blood cells.

Note:
Enterochromaffin-like cells, located in the gastric pits of the fundus and cardia regions of the stomach, release histamine, which then attaches to H2 receptors on the parietal cells near it and further initiates the release of gastric acid by parietal cells. Acinar cells, located in the pancreas, are responsible for the production, storage, and secretion of pancreatic digestive enzymes. Gastrin attaches to CCK2 receptors located on the acinar cells, inducing secretion of the cell’s stored digestive enzymes.