Which of the following hormones primarily stimulates the release of hydrochloric acid and pepsin?

Bihar NHM CHO-2025

Applied Physiology

Easy

Appeared in: Bihar NHM CHO-2025

Explanation

Gastrin is the primary hormone that stimulates gastric acid (HCl) and pepsin secretion.
It is produced by G cells located in the antrum of the stomach.
Gastrin acts on parietal cells to release HCl and on chief cells to release pepsinogen, the precursor to pepsin.
This hormonal action is a key part of the gastric phase of digestion, triggered by the presence of food (especially proteins) in the stomach.

Option A: Motilin's primary role is to regulate gastrointestinal motility, specifically by initiating the migrating motor complex (MMC) during fasting periods to 'sweep' the intestines clean. It does not stimulate acid secretion.
Option B: Cholecystokinin (CCK) is released from the duodenum in response to fats and proteins. Its main functions are to stimulate gallbladder contraction (releasing bile) and pancreatic enzyme secretion. It actually inhibits gastric acid secretion and slows gastric emptying.
Option D: Secretin is released from the duodenum in response to acidic chyme. Its primary function is to stimulate the pancreas to release bicarbonate-rich fluid to neutralize the acid. It acts as an inhibitor of gastric acid secretion, opposing the action of gastrin.

Visual 1: Diagram: Hormonal control of digestion, showing the stomach, duodenum, pancreas, and gallbladder with arrows indicating the release and target organs of Gastrin, CCK, and Secretin.
Visual 2: Flowchart: The process of gastric acid secretion, starting from food intake, leading to gastrin release, and culminating in HCl and pepsinogen secretion.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal Regulation of Gastric Secretion as background academic context rather than a clinical decision trigger.
Understanding the role of gastrin is crucial for comprehending conditions like Zollinger-Ellison syndrome, where a gastrin-producing tumor (gastrinoma) leads to hypersecretion of gastric acid, causing severe peptic ulcers.
Many common medications for acid reflux and peptic ulcer disease, such as proton pump inhibitors (e.g., omeprazole) and H2 blockers (e.g., ranitidine), work by targeting the pathways stimulated by gastrin to reduce acid production.
What if? If a patient has chronic atrophic gastritis with destruction of parietal cells, they would have low acid production (achlorhydria). This lack of acid removes the negative feedback on G cells, leading to abnormally high levels of gastrin in the blood.

How to Approach the Question

First, identify the key substances in the question: hydrochloric acid and pepsin. Recall that these are the main components of gastric juice, responsible for digestion in the stomach.
The question asks which hormone stimulates their release. This requires knowledge of the major gastrointestinal hormones.
Systematically review the function of each option: Motilin (motility), CCK (gallbladder/pancreas), Gastrin (gastric acid), and Secretin (bicarbonate/inhibition of acid).
Match the function to the question. Gastrin is the only hormone listed whose primary role is to stimulate gastric acid and pepsinogen secretion.
Therefore, select Gastrin as the correct answer.

Concept Tested & Keywords

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