Albert, the patient in question 3, takes the drug lithium, which reduces the permeability of the neuronal axolemma to Na+ (that is, it allows fewer Na+ to enter the axon). Predict the effect this would normally have on his neuronal action potentials. Do you think this drug would be beneficial or harmful, considering his condition?

Verified step by step guidance

1. Understand the role of Na+ in action potentials: Sodium ions (Na+) are crucial for the depolarization phase of an action potential. When Na+ channels open, Na+ rushes into the neuron, causing the inside to become more positive.
2. Consider the effect of reduced Na+ permeability: If lithium reduces the permeability of the neuronal axolemma to Na+, fewer Na+ ions will enter the neuron during depolarization.
3. Predict the impact on action potentials: With fewer Na+ ions entering, the depolarization phase will be less pronounced, potentially leading to a weaker or slower action potential.
4. Evaluate the potential benefits: In conditions where excessive neuronal firing is problematic, such as in certain mood disorders, reducing action potential frequency or intensity might be beneficial.
5. Assess potential harm: Conversely, if the condition requires normal or enhanced neuronal activity, reducing action potential strength could be detrimental.

Key Concepts

Neuronal Action Potentials

Neuronal action potentials are rapid changes in the electrical membrane potential of a neuron that occur when it is stimulated. This process involves the influx of sodium ions (Na+) through voltage-gated sodium channels, leading to depolarization. The action potential is crucial for the transmission of signals along the axon and communication between neurons.

Sodium Ion Permeability

Sodium ion permeability refers to the ability of the neuronal membrane to allow Na+ ions to pass through. When the permeability is high, Na+ ions enter the neuron rapidly, contributing to depolarization and the generation of action potentials. Conversely, reducing this permeability, as lithium does, decreases the likelihood of action potentials occurring, which can affect neuronal signaling.

Lithium's Mechanism of Action

Lithium is a mood-stabilizing medication commonly used to treat bipolar disorder. It works by altering the balance of neurotransmitters in the brain and reducing the excitability of neurons. By decreasing Na+ permeability, lithium can dampen excessive neuronal firing, which may be beneficial in conditions characterized by hyperactivity but could also impair normal neuronal function if overused.