which of the following not secreted by the GI tract ?
Gastrin
EPO
Secretin
The correct answer and explanation is:
The correct answer is EPO.
Erythropoietin (EPO) is not secreted by the gastrointestinal (GI) tract. EPO is a hormone primarily produced by the kidneys, although it is also secreted by the liver in small amounts during fetal development. The primary function of EPO is to regulate the production of red blood cells (erythropoiesis) by stimulating the bone marrow when oxygen levels in the blood are low.
On the other hand, gastrin and secretin are both secreted by the GI tract.
- Gastrin is produced by G-cells in the stomach. It stimulates the secretion of gastric acid (HCl) from parietal cells and plays a key role in the digestive process, especially in the breakdown of food. Gastrin is released in response to food entering the stomach or when the stomach is stretched.
- Secretin is produced by S-cells in the duodenum, which is the first part of the small intestine. It is released when acidic chyme enters the duodenum from the stomach. Secretin helps regulate the pH of the duodenum by stimulating the pancreas to secrete bicarbonate, which neutralizes stomach acid. It also inhibits gastric acid secretion and motility.
Both gastrin and secretin play vital roles in regulating digestive processes, while EPO has a completely different function related to red blood cell production, and its source is outside the GI tract.