How do nerves conduct impulses?

Nerves conduct impulses primarily through depolarization of the nerve membrane. When a neuron receives a stimulus strong enough to reach a certain threshold, the permeability of the neuronal membrane to sodium ions changes dramatically. This allows sodium ions to flow into the cell, leading to a rapid increase in the membrane potential, which is known as depolarization.

This change in voltage propagates along the neuron in the form of an action potential, allowing the nerve signal to travel down the axon to the next neuron or to the target tissue. This process is critical for the transmission of impulses throughout the nervous system, enabling communication between different parts of the body.

While other options mention aspects related to nerve function or communication, they are not the primary mechanism of impulse conduction within the neuron itself. For instance, hyperpolarization generally occurs after an action potential and serves to reset the membrane potential, increasing the threshold needed for the next impulse. Increasing extracellular calcium concentration is more relevant to certain types of synaptic transmission but is not a direct mechanism for conducting impulses along axons. Chemical transmission between synapses refers to how signals are transmitted from one neuron to another but does not pertain to the conduction of impulses along an individual nerve fiber.