Difference Between Secretin and Cholecystokinin

The key difference between secretin and cholecystokinin is that the secretin is a peptide hormone produced by S cells of the duodenum and jejunum while the cholecystokinin is another peptide hormone secreted by I cells of the duodenum.

Hormones are chemicals synthesized by endocrine glands. They regulate most of the bodily functions. Moreover, different types of organs secrete different hormones. Among the different types of organs, the gastrointestinal tract is an organ that secretes hormones that are essential for the food digestion, and related functions. Different parts of the GI tract also secrete hormones. Moreover, duodenum also secretes several essential hormones. Among them, secretin and cholecystokinin are two hormones produced and secreted together when foods reach the stomach. Both hormones are peptide hormones that are responsible for regulating stomach secretions and maintaining an alkaline environment in the duodenum contents.

CONTENTS

1. Overview and Key Difference
2. What is Secretin
3. What is Cholecystokinin
4. Similarities Between Secretin and Cholecystokinin
5. Side by Side Comparison – Secretin vs Cholecystokinin in Tabular Form
6. Summary

What is Secretin?

The S cells of the duodenum and jejunum produce and secrete Secretin, which is a peptide hormone. It comprised of 27 amino acid linear peptide. Secretin remains as an inactive form called prosecretin. This hormone is mainly responsible for the water homeostasis of the body.

Furthermore, it influences the environment of the duodenum by regulating the stomach, pancreas and liver secretions.

What is Cholecystokinin?

Cholecystokinin is one of the duodenum hormones. It is also a peptide hormone secreted by enteroendocrine cells in the mucosal lining of the small intestine called I cells.

Cholecystokinin acts as a neuropeptide in the central nervous system as well as acts as a peptide hormone in the gut. Hence, it is responsible for stimulating digestion of proteins in the gut. Furthermore, cholecystokinin involves in the fat digestion as well.

What are the Similarities Between Secretin and Cholecystokinin?

• Cholecystokinin and secretin are two duodenal gland hormones.
• They are peptide hormones.
• Furthermore, they secrete together by duodenum when food reaches the stomach.
• Also, both hormones have inhibitory effects on motor and secretory functions of the stomach.
• Besides, they help to maintain an alkaline environment in the duodenal contents by increasing the flow of both pancreatic juice and hepatic bile.

What is the Difference Between Secretin and Cholecystokinin?

Secretin and cholecystokinin are two types of hormones of the duodenum. S cells of the duodenum secrete secretin while I cells of the duodenum secrete cholecystokinin. It is the key difference between secretin and cholecystokinin.

Furthermore, secretin is a linear peptide consisting of 27 amino acid sequence, while cholecystokinin exists as three forms; consisting of 33, 59, and 385 amino acid sequences. Therefore, this is another difference between secretin and cholecystokinin. Also, secretin is mainly responsible for water homeostasis while cholecystokinin is mainly responsible for fat and protein digestion. Hence, this is another difference between secretin and cholecystokinin.

The below infographic shows more information on the difference between secretin and cholecystokinin.

Summary – Secretin vs Cholecystokinin

Secretin and cholecystokinin are two duodenal hormones. Both are peptide hormones secreting together when food reaches the stomach. In summarizing the difference between secretin and cholecystokinin, the S cells of the duodenum secrete secretin while the I cells of the duodenum secrete cholecystokinin. Also, secretin is a linear peptide comprising of 27 amino acid sequence, while cholecystokinin is a peptide hormone that exists in three types consisting of 33, 59 and 385 amino acid sequences. However, both are responsible for the regulation of stomach secretions and maintaining an alkaline environment in the duodenum.

Reference:

1. “Secretin.” Wikipedia, Wikimedia Foundation, 25 July 2018. Available here  
2“Cholecystokinin.” NeuroImage, Academic Press. Available here

Image Courtesy:

1.”Tractus intestinalis duodenum”By Olek Remesz – Own work, (CC BY-SA 2.5) via Commons Wikimedia  
2.”Effects of CCK on the gastrointestinal tract”By McortNGHH – Own work, (CC BY-SA 4.0) via Commons Wikimedia