What is the nerve cell that convey impulses from the central nervous system to the periphery?

RRB Staff Nurse Jaipur-6th June 2018

Applied Physiology

Easy

Appeared in: RRB Staff Nurse Jaipur-6th June 2018

Explanation

Efferent neurons, also known as motor neurons, are responsible for transmitting signals from the central nervous system (CNS) to the periphery.
These signals travel to effector organs, such as muscles and glands, to initiate a response like muscle contraction or gland secretion.
The term 'efferent' originates from Latin, meaning 'to carry away from,' which describes the direction of impulse flow away from the CNS.

Option A: This is a misspelling of cilia, which are hair-like organelles on the surface of cells responsible for movement. They are not nerve cells and do not transmit impulses.
Option B: Afferent neurons carry impulses in the opposite direction, from the peripheral sensory receptors towards the central nervous system.
Option C: A dendrite is a part of a neuron, not a type of neuron in this classification. Its function is to receive signals from other neurons and conduct them towards the cell body.

Visual 1: Diagram of a Reflex Arc. This visual should clearly label the sensory (afferent) neuron carrying a signal from a receptor (e.g., skin), the interneuron within the spinal cord, and the motor (efferent) neuron carrying the response signal to an effector (e.g., muscle).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of neurons based on the direction of impulse transmission as background academic context rather than a clinical decision trigger.
Understanding the difference between afferent and efferent pathways is fundamental for diagnosing neurological disorders. Damage to efferent nerves (motor pathways) can result in muscle weakness, paralysis, or spasms.
This knowledge is crucial for nurses performing neurological assessments. Testing a patient's reflexes, muscle strength, and response to stimuli helps evaluate the integrity of both afferent and efferent pathways.
What if? If a patient can feel a pinprick on their foot (intact afferent pathway) but cannot move their toes in response (impaired efferent pathway), it points to a motor nerve or CNS motor neuron lesion, rather than a sensory one.

How to Approach the Question

First, break down the question to identify the direction of impulse flow. The key phrase is 'from the central nervous system to the periphery'.
This indicates the signal is moving away from the CNS.
Recall or use a mnemonic to differentiate between afferent and efferent. A useful one is that 'Efferent' signals 'Exit' the CNS, while 'Afferent' signals 'Arrive' at the CNS.
Evaluate the options based on this directional flow. 'Efferent neuron' matches the 'exit' direction.
Eliminate the other options. 'Celia' is not a neuron. 'Dendrite' is a part of a neuron, not a classification based on CNS direction. 'Afferent neuron' describes the opposite direction of signal flow.

Concept Tested & Keywords

Concept Tested: Classification of neurons based on the direction of impulse transmission
Stem keywords: nerve cell, impulses, central nervous system, periphery
Lead-in keywords: What is

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