Some drugs may act on all types of neurons by:

• A. stimulating only the myelin sheath production in sensory neurons
• B. inhibiting the synthesis of neurotransmitters specific to only motor neurons
• C. blocking synaptic vesicle release exclusively in interneurons
• D. altering the permeability of the neuronal membrane to ions

Answer: (D)

Verified step by step guidance

1. Understand the structure and function of a neuron: Neurons consist of a cell body, dendrites, axon, and synaptic terminals. The neuronal membrane plays a critical role in maintaining the resting membrane potential and facilitating action potentials through ion permeability.
2. Review the concept of ion permeability: The neuronal membrane contains ion channels that regulate the movement of ions such as sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺), and chloride (Cl⁻). These channels are essential for generating and propagating electrical signals in neurons.
3. Recognize how drugs can alter ion permeability: Some drugs can affect the function of ion channels by either blocking or enhancing their activity. This can disrupt the normal flow of ions across the membrane, impacting the neuron's ability to generate action potentials and communicate with other neurons.
4. Understand why altering ion permeability affects all types of neurons: Unlike the other options provided, which target specific types of neurons (sensory, motor, or interneurons), altering ion permeability impacts a fundamental property of all neurons, regardless of their type. This makes it a universal mechanism of action.
5. Conclude that altering the permeability of the neuronal membrane to ions is the correct answer because it affects the basic electrical properties of all neurons, making it a mechanism that applies broadly rather than selectively to specific neuron types.