All the following enzymes are secreted by gastrointestinal system EXCEPT

JIPMER Nursing Officer-2017

Biochemistry & Nutrition

Easy

Appeared in: JIPMER Nursing Officer-2017

Explanation

Angiotensin is the correct answer because it is a hormone, not a digestive enzyme.
It is a central component of the Renin-Angiotensin-Aldosterone System (RAAS), which regulates blood pressure and electrolyte balance.
Its precursor, angiotensinogen, is made by the liver, but it is activated by renin (from the kidneys) and angiotensin-converting enzyme (ACE, from the lungs), placing it outside the primary digestive functions of the GI tract.

Option A: Ptyalin (salivary amylase) is incorrect because it is a digestive enzyme secreted by the salivary glands in the mouth, which is the starting point of the gastrointestinal tract.
Option B: Pepsin is incorrect because it is a key proteolytic (protein-digesting) enzyme secreted by the chief cells of the stomach.
Option C: Chymotrypsin is incorrect because it is a digestive enzyme produced by the pancreas (an accessory GI organ) and secreted into the small intestine to break down proteins.

Clinical Relevance

Nursing practice connection: Knowing Digestive Enzymes of the Gastrointestinal System helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding the difference between digestive enzymes and systemic hormones is fundamental in nursing. Misinterpreting their roles can lead to errors in patient assessment and education.
Knowledge of the RAAS system is critical for managing patients with hypertension, as many antihypertensive medications (e.g., ACE inhibitors, ARBs) target this pathway.
Elevated levels of digestive enzymes like amylase and lipase in the blood are key diagnostic markers for pancreatitis, a condition where these enzymes prematurely activate and damage the pancreas.

How to Approach the Question

First, identify the core of the question. It asks for the item that is an EXCEPTION, meaning it does not fit with the others.
The category is 'enzymes secreted by the gastrointestinal system'.
Review each option: Ptyalin, Pepsin, and Chymotrypsin are all well-known digestive enzymes associated with the mouth, stomach, and pancreas/small intestine, respectively.
Consider Angiotensin. Recall its function. Angiotensin is primarily known for its role in the Renin-Angiotensin-Aldosterone System (RAAS), which regulates blood pressure.
Conclude that Angiotensin is the outlier. It is a hormone involved in a systemic regulatory pathway, not a digestive enzyme secreted by the GI tract for breaking down food.
Therefore, Angiotensin is the correct answer to the 'EXCEPT' question.

Concept Tested & Keywords

Concept Tested: Digestive Enzymes of the Gastrointestinal System
Stem keywords: enzymes, gastrointestinal system
Lead-in keywords: EXCEPT
Negative lead-in flag: The question asks for the EXCEPTION, meaning the item that does NOT belong to the group of enzymes secreted by the GI system.

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