Final answer:
Neurons can be considered both voltage and current sources during signal transmission. The axon conducts electrical signals, and neurons can be part of the CNS or PNS depending on their location with efferent nerves carrying signals from the CNS to muscles.
Step-by-step explanation:
When a signal is sent from one part of the brain to another, neurons can be thought of as both voltage sources and current sources. This is because the initial action potential is a result of a voltage change across the neuron's membrane, which then drives a current along the axon. Specifically, this voltage change is responsible for opening ion channels, which results in a flow of ions that constitute the electrical current.
The axon is the part of a neuron that transmits an electrical signal to a target cell. The signal from neuron A is transmitted to neuron B via a chemical synapse. Neuron A would be part of the central nervous system (CNS) if it is located in the brain or spinal cord. The nerve containing the axon of neuron B traveling to a skeletal muscle cell would be part of the peripheral nervous system (PNS) and would represent an efferent nerve, as it is carrying signals away from the CNS to effect a response in the muscle.