Neurotransmitters?

Appeared in: NHM UP Staff Nurse - 2016

Explanation

Neurotransmitters are defined as chemical signal molecules.
They are released from the presynaptic neuron's axon terminal into the synapse.
Their function is to transmit a signal from one neuron to a target cell (another neuron, muscle, or gland).
This process of chemical signaling across a synapse is called neurotransmission.

Option A: This confuses the chemical signal between neurons with the electrical signal along a neuron. An action potential is an electrical impulse, but a neurotransmitter is a chemical substance.
Option B: Neurotransmitters are present in all neurons that communicate via chemical synapses, regardless of whether they are myelinated or unmyelinated.
Option D: Neurotransmitters are synthesized and released by neurons (nerve cells), not muscle cells.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Definition and function of neurotransmitters as background academic context rather than a clinical decision trigger.
Understanding neurotransmitters is crucial as imbalances are linked to many neurological and psychiatric disorders. For example, low dopamine levels are a hallmark of Parkinson's disease, while imbalances in serotonin are associated with depression and anxiety.
Many pharmacological treatments work by targeting neurotransmitter systems. For instance, Selective Serotonin Reuptake Inhibitors (SSRIs) increase serotonin levels in the synapse to treat depression.
Nurses must be aware of the side effects of medications that affect neurotransmitters, such as anticholinergic drugs that block acetylcholine and can cause dry mouth, confusion, and constipation.

How to Approach the Question

First, identify the core concept of the question, which is the definition of 'Neurotransmitters'.
Recall the fundamental role of a neurotransmitter in the nervous system. It is a chemical used for communication between cells.
Evaluate each option based on this core definition.
Option A describes an electrical impulse, which is how a signal travels along a neuron, not between them. Eliminate this.
Option B makes a limiting statement about myelination. Myelination affects conduction speed, not the existence of chemical signaling. This is an incorrect restriction. Eliminate this.
Option C describes them as 'signal molecules released at synapses', which perfectly matches the definition of a chemical messenger acting at the junction between neurons. This is a strong candidate.

Concept Tested & Keywords

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E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 2 — Subpart B (pp 240-463 of 478) p. 128-130

E6 Psychology Applied Sreevani 6e Sem1 p. 45-47

E6 Anatomy Grays 43e Vol 1 Part 1 p. 81-83

Practise the full NHM UP Staff Nurse - 2016

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