Electrical potential, often measured in volts, represents the potential energy per unit charge. In biological systems, this refers to the difference in electrical charge between two points, such as the inside and outside of a cell membrane. This potential difference is what drives the flow of ions across the membrane, enabling the generation of electrical signals like action potentials in neurons.

An action potential is a rapid sequence of changes in the voltage across a membrane. This process involves electrical changes, specifically the depolarization and repolarization of the membrane potential, and chemical changes, which involve the movement of ions like sodium and potassium across the neuronal membrane through specific ion channels.

An action potential is a rapid, temporary change in the electrical membrane potential of a neuron. When the threshold of excitation is reached, the neuron depolarizes, sending an electrical signal down the axon to facilitate communication between neurons.

Nissl bodies, or Nissl granules, are large granular bodies found in neurons. They are composed of rough endoplasmic reticulum (RER) with rosettes of free ribosomes and are the site of protein synthesis. These structures are essential for the production of neurotransmitters and the maintenance of the neuronal membrane, appearing as dark patches under a microscope within the soma.

A neuron consists of a cell body (soma), dendrites, and an axon with axon terminals. The synapse is not a part of the neuron itself; rather, it is the specialized junction or gap between two neurons where chemical or electrical signals are transmitted. Therefore, the synapse is an external space between cells, not an internal structural component of the neuron.

The resting membrane potential is primarily established by the selective permeability of the neuronal membrane to potassium ions. Because the membrane is more permeable to K+ at rest, these ions diffuse out of the cell down their concentration gradient, leaving behind negatively charged organic molecules. While the sodium-potassium pump is essential for maintaining the concentration gradients over time, the outward diffusion of K+ is the direct cause of the negative charge.

The generation of an action potential involves the rapid influx of sodium ions (Na+) and the efflux of potassium ions (K+). This movement changes the membrane potential and causes a temporary reversal of the electrical charge across the neuronal membrane, which is essential for signal transmission.

The soma, also referred to as the cell body or perikaryon, is the metabolic center of the neuron. It houses the nucleus and organelles necessary for protein synthesis and cellular maintenance, acting as the integration point for signals received from the dendrites before they are sent down the axon.

Communication within a neuron occurs via electrical signals known as action potentials, which travel down the axon. Communication between neurons occurs across the synapse through the release of chemical messengers called neurotransmitters. This electrochemical process is essential for the transmission of information throughout the nervous system, allowing for complex neural signaling and integration.

A neuron transmits an impulse during the active membrane potential, also known as the action potential. This occurs when the membrane depolarizes beyond a threshold, triggering a rapid, self-propagating electrical signal. Resting potential is the state of readiness before firing, while threshold is the minimum stimulus required to trigger the active state.