Which of the following is not a neurotransmitter?

Appeared in: SCTIMST Staff Nurse - 2016

Explanation

Troponin is a complex of regulatory proteins (Troponin C, I, and T) that is fundamental to the process of muscle contraction in skeletal and cardiac muscle fibers.
It is not a chemical messenger that transmits signals between neurons, which is the defining role of a neurotransmitter.
Clinically, elevated blood levels of cardiac-specific troponins (cTnI and cTnT) are the gold standard biomarker for diagnosing myocardial injury, such as a heart attack.

Option A: Epinephrine (also known as adrenaline) is a well-known catecholamine that functions as both a hormone and an excitatory neurotransmitter.
Option B: Dopamine is a key catecholamine neurotransmitter in the central nervous system.
Option C: Gamma-Aminobutyric Acid (GABA) is the primary inhibitory neurotransmitter in the brain.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Differentiating neurotransmitters from other biomolecules as background academic context rather than a clinical decision trigger.
The measurement of cardiac troponin is a cornerstone of modern cardiology for the diagnosis and risk stratification of patients with acute coronary syndromes, including heart attacks.
A nurse must be able to recognize that a lab report showing elevated troponin levels is a critical finding that indicates heart muscle damage and requires immediate attention.
Understanding the roles of neurotransmitters like dopamine and GABA is essential for administering and monitoring medications for psychiatric and neurological disorders (e.g., antipsychotics, anti-anxiety drugs, and treatments for Parkinson's disease).

How to Approach the Question

First, carefully read the question and identify the negative keyword 'not'. This means you are looking for the option that is the exception.
The question asks to find the substance that is NOT a neurotransmitter. Recall the definition of a neurotransmitter: a chemical messenger that transmits signals between nerve cells.
Evaluate each option against this definition.
Epinephrine, Dopamine, and GABA are all classic examples of neurotransmitters involved in various functions of the nervous system.
Consider Troponin. Recall or deduce its function. Troponin is a protein associated with muscle tissue, specifically with the process of contraction.
Since Troponin's function is mechanical (muscle contraction) rather than signaling (nerve transmission), it is the correct answer as it is not a neurotransmitter.

Concept Tested & Keywords

Concept Tested: Differentiating neurotransmitters from other biomolecules
Stem keywords: neurotransmitter, not
Lead-in keywords: not
Negative lead-in flag: This is a negative-lead question asking you to identify the option that does NOT fit the category of a neurotransmitter.

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E6 Physiology Essentials Sembulingam 10e Part 3 p. 62-64

Practise the full SCTIMST Staff Nurse - 2016

Attempt every question from this paper in a timed mock, then review the full solution for each one.