Final answer:
Local anesthetics such as lidocaine work by blocking sodium channels, which prevents the propagation of nerve impulses, leading to a temporary loss of sensation or numbness in the area where they are applied.
Step-by-step explanation:
The nurse knows that local anesthetics work by blocking sodium channels. This biological action occurs because local anesthetics like lidocaine are Na+ channel blockers, which prevent sodium from moving across the neuronal membrane. When sodium channels are blocked, it inhibits the propagation of the electrical signal along the nerve, thus preventing the sensation of pain and resulting in numbness.
Neurons transmit information by generating electrical signals, known as action potentials, which travel along the nerve fiber. This process involves the rapid influx and outflux of sodium and potassium ions across the neuron's membrane. The action of lidocaine as a sodium channel blocker hinders this ion movement, thereby ceasing the propagation of the action potential. Without the transmission of these signals, the perception of pain is temporarily lost as the neuronal communication with the brain is interrupted.