GED Science TestLife ScienceMedium
A client presents with symptoms including general fatigue, muscle weakness, and impaired coordination. A neurologist performs several tests and determines that the client's myelin sheaths are progressively deteriorating. Based on this information, which of the following processes is most likely being disrupted?
- AReuptake of neurotransmitters into the presynaptic neuron
- BRapid transmission of electrical signals along the axon
- CNeurotransmitter synthesis at the synapse
- DGeneration of action potentials in the dendrites
Show answer & explanationAnswer & explanation
Correct answer: B. Rapid transmission of electrical signals along the axon
The myelin sheath acts as an insulating layer around axons, allowing for the rapid and efficient transmission of electrical signals (action potentials). Its deterioration directly impairs the speed and efficiency of nerve impulse conduction.
Why the other options are wrong
- A. Reuptake of neurotransmitters occurs at the synapse and is primarily related to synaptic function, not axonal conduction speed.
- C. Neurotransmitter synthesis occurs within the neuron and is not directly affected by myelin sheath integrity.
- D. Action potentials are typically generated at the axon hillock, not primarily in the dendrites, and their generation is distinct from the speed of their propagation along the axon.
Myelin Sheath Function
An insulating layer, primarily composed of lipids and proteins, that forms around nerves, including those in the brain and spinal cord, allowing electrical impulses to transmit quickly and efficiently along the nerve cells.
- Increases nerve impulse conduction speed.
- Protects axons.
- Formed by Schwann cells (PNS) and oligodendrocytes (CNS).
Memory trick: My Fast Nerves Relay Signals.