Secretin is released from S cells of the duodenum in response to acid. Its primary action on the pancreas produces pancreatic juice with which distinctive characteristic?

• A Large volume of enzyme-rich juice with low bicarbonate
• B Small volume of concentrated enzyme-rich juice
• C Bicarbonate-poor juice that activates CCK-mediated enzyme release
• D Large volume of HCO3-rich juice with relatively low enzyme content ✓

Explanation

Secretin, acting via cAMP on pancreatic ductal cells (centroacinar cells), stimulates large-volume, bicarbonate-rich pancreatic juice with relatively low enzyme content. This juice neutralises gastric acid entering the duodenum, creating the appropriate pH for pancreatic enzyme function. CCK (from I cells), in contrast, primarily stimulates enzyme-rich pancreatic secretion from acinar cells. The two hormones act synergistically: secretin provides volume/HCO3, CCK provides enzymes.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.