Release of pancreatic juice is stimulated by which of the following?

UPPSC 2017

Applied Physiology

Easy

Appeared in: UPPSC 2017

Explanation

Cholecystokinin (CCK) is a hormone released from the I-cells of the duodenum and jejunum.
Its release is triggered by the presence of fats (fatty acids) and proteins (amino acids, peptones) in the chyme entering the small intestine.
CCK's primary action on the pancreas is to stimulate the acinar cells, causing them to secrete a large volume of pancreatic juice that is rich in digestive enzymes (e.g., amylase, lipase, trypsinogen).
This enzyme-rich secretion is crucial for the chemical digestion of macronutrients in the small intestine.

Option A: Enterokinase (also known as enteropeptidase) is an enzyme, not a hormone. It does not stimulate pancreatic secretion.
Option C: Trypsinogen is an inactive proenzyme (zymogen) that is a component of pancreatic juice. It is a product of pancreatic secretion, not a stimulus for it.
Option D: While Secretin does stimulate pancreatic secretion, its primary role is to cause the release of a watery, bicarbonate-rich fluid from the pancreatic ductal cells to neutralize stomach acid. It is not the main stimulus for the release of digestive enzymes.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of exocrine pancreatic secretion as background academic context rather than a clinical decision trigger.
Understanding the roles of CCK and secretin is vital in diagnosing conditions like exocrine pancreatic insufficiency (EPI), where the pancreas doesn't produce enough digestive enzymes, leading to malabsorption, steatorrhea (fatty stools), and weight loss.
In diagnostic procedures, a 'secretin stimulation test' can be used to assess pancreatic function by measuring the volume and bicarbonate content of pancreatic secretions after administering synthetic secretin.
What if? - If a patient has a condition like celiac disease that damages the duodenal mucosa, the ability to release CCK and secretin can be impaired. This would lead to reduced pancreatic stimulation, contributing to maldigestion and malabsorption, even if the pancreas itself is healthy.

How to Approach the Question

First, identify the core physiological process in the question: the stimulation of pancreatic juice release.
Recall the key substances involved in regulating digestion. This should bring to mind hormones and enzymes.
Analyze each option's function: Is it a hormone that stimulates secretion, an enzyme that activates another substance, or a product that is secreted?
Eliminate options that are not stimulating hormones (Enterokinase is an enzyme, Trypsinogen is a proenzyme).
This leaves two hormones: Cholecystokinin (CCK) and Secretin. Differentiate their specific roles.
Recall that CCK responds to food (fats/proteins) and stimulates enzyme release, while Secretin responds to acid and stimulates bicarbonate release. Since 'pancreatic juice' for digestion primarily refers to the enzymes, CCK is the most appropriate answer.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 2A p. 175-177

E6 Medicine Harrison 22e Part 2 p. 647-649