The speed of an action potential is primarily determined by the diameter of the axon and the presence of a myelin sheath. A larger diameter reduces internal resistance, while the myelin sheath allows for saltatory conduction, where the impulse jumps between nodes of Ranvier. Therefore, thick, myelinated fibers exhibit the highest conduction velocities.

The resting potential is the stable, negative electrical charge of a neuron when it is not actively transmitting a signal. This state is maintained by the unequal distribution of ions inside and outside the cell membrane. It is a crucial baseline that allows the neuron to be ready to fire an action potential when it receives sufficient stimulation.

In the peripheral nervous system, nerves are defined as cable-like bundles of axons or dendrites wrapped in connective tissue sheaths. These structures serve as the primary pathways for transmitting electrochemical signals between the central nervous system and the rest of the body.

White matter in the central nervous system derives its color from the high concentration of myelin, a fatty substance that insulates axons. Myelin increases the speed of electrical signal transmission between different regions of the brain and spinal cord. In contrast, gray matter is primarily composed of neuronal cell bodies, dendrites, and unmyelinated axons, which are involved in processing and interpreting information.

White matter in the central nervous system derives its name from the appearance of myelin, a fatty substance that insulates axons. This myelin sheath facilitates rapid signal transmission between different regions of the brain and spinal cord, distinguishing white matter from gray matter, which consists primarily of neuronal cell bodies and dendrites.

The absolute refractory period is the interval immediately following an action potential during which the neuron is incapable of firing another impulse, regardless of the stimulus intensity. This period sets a physical limit on the frequency of neural firing.

An action potential is a rapid, temporary change in the electrical membrane potential of a cell. When a stimulus reaches the threshold, the membrane potential reverses from its negative resting state to a positive value due to the rapid influx of sodium ions. This reversal of charge is the fundamental mechanism by which neurons transmit information across long distances in the nervous system.

Action potentials follow the 'all-or-none' principle, meaning they do not vary in size or speed based on stimulus intensity. Instead, the nervous system encodes the strength of a stimulus by increasing the frequency or rate at which neurons fire action potentials over a given period.

Efferent fibers, also known as motor neurons, are responsible for carrying signals away from the central nervous system toward the muscles and glands. When the brain initiates movement, such as walking, it sends these motor commands through efferent pathways to trigger muscle contraction.

Motor neurons, also known as efferent neurons, are specialized nerve cells that carry electrical impulses away from the central nervous system toward effectors, such as muscles and glands. This process allows the body to execute physical movements and physiological responses to stimuli. Other options listed are either biological processes or brain structures rather than specific neuron types.