Neurons, or nerve cells, are the electrically excitable cells that make up most of the nervous system. A unipolar neuron has only one attachment or process arising from the main portion of the cell. The most common type of unipolar neuron is a sensory neuron that carries signals into the central nervous system, which is made up of the brain and spinal cord.
A unipolar neuron differs from other types of neurons by having only one process that arises from the main portion of the cell, or cell body. Most neurons in the body have many processes, one axon and many sensory processes called dendrites. The process of a unipolar neuron is mostly axon but also has a sensory dendrite on one end.
Neurons are made of three main parts: a cell body, an axon and one to several dendrites. The cell body is the portion of a neuron that contains normal cell parts. The dendrites carry sensory information from other neurons, receptors or the body toward the cell body. The one axon of a neuron does the electrical and chemical signaling of the neuron that is carried onto another neuron or another cell.
The axon of a neuron does electrical signaling, meaning that it carries an electrical charge, similar to an electrical wire carrying electricity. When the electrical signal reaches the end of the axon, a chemical signal is released to signal the next neuron. This combination of electrical and chemical signaling gives the nervous system greater control over what information it can convey.
Outside of the spinal cord and brain, the axons of nerve cells have the unique ability to regenerate and repair themselves after damage. Damage to the cell body of a nerve cell, however, will result in the death of that nerve cell. Nerve cells, unlike many other types of cells in the body, are not capable of division, meaning that the body can not make new nerve cells to replace dead ones.
A type of nerve cell called a sensory neuron is responsible for carrying signals into the central nervous system. Most sensory neurons are classified as unipolar neurons. A sensory dendrite on the far end of the axon detects changes inside or outside of the body, then an electrical signal is carried down the axon into the central nervous system. The structure of a unipolar neuron is unique, and the cell body of this nerve cell is protected by the backbones or skull bones. The single attachment or process of a unipolar neuron is the only part of the neuron out in the rest of the body, but it has the ability to repair itself.