An increase in extracellular potassium (K⁺) concentration will lead to depolarization of the neuron's membrane. This is because higher levels of potassium outside the cell reduce the concentration gradient for potassium ions, making it less negative inside the neuron. As a result, the neuron's resting membrane potential becomes less negative (or depolarized).
When a neuron becomes depolarized, this change in membrane potential can influence the activity of nearby axons. Specifically, if the depolarization reaches a certain threshold, it can trigger action potentials in nearby axons. This is due to the following reasons:
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Local Change in Membrane Potential: The depolarization in one region can create local currents, which can depolarize adjacent regions of the membrane.
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Threshold Potential: If the local depolarization is sufficient to bring nearby axonal membranes to the threshold potential, it can activate voltage-gated sodium channels, leading to the generation of action potentials in those axons.
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Propagation of Activity: If action potentials are generated in nearby axons, they can propagate along the axon, potentially affecting communication between neurons.
In summary, the nearby axonal membranes will become depolarized, and if the depolarization is sufficient, this could lead to action potentials being generated in those axonal segments, facilitating neuronal signaling in the surrounding area.
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