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Diagram of a nerve cellNeurons are the specialized cells of the nervous system. The neurons are responsible for the transmission of electrical impulses to and from the central nervous system. The main structures of the neuron are, the cell body, the axon, and the dentrite. Each neuron is equipped with hundreds of dentrites, but only one axon. This places an enormous importance on the axon. The synaptic cleft is also an important feature of neurons. The synaptic cleft is a region of the neuron. It is the area between neurons. This region is responsible for the separation of neurons. The neuron is composed of dentrites, the soma, the axon, and a cell body. The cell body contains the normal organelles; such as mitochondria and the endoplasmic reticulum. The size of neurons differs, but neurons usually range from two to five hundred microns in diameter.

miscells.gif (726 bytes) Other then neurons there are a few other cells which are particular to the nervous system. For example, ganglia are small bodies of cell bodies located within the nervous system. Ganglion are primarily found in the peripheral nervous system. Tracts are another formation found within the nervous system. Tracts are bundles of nerve fibers also know as neuron processes. Tracts primarily run throughout the peripheral nervous system.

schwann.gif (966 bytes) One of the more important features of the neuron, is the Schwann Cell. The Schwann cell is responsible for three jobs; the enclosing of the axon, the insulation of the axon, and the protection of the axon. The Schwann Cell accomplishes its responsibility to the axon through the myelin sheath. The myelin sheath is a process formed by the Schwann Cell, protecting, insulating, and enclosing the axonal cylinder. Schwann Cells are formed by a white matter. The white matter of Schwann Cells is actually fatty matter in a liquid state. The white matter of Schwann Cells encloses and insulates the axonal cylinder. The thickness of the white matter varies. The white matter of the Schwann cell id the main component of the myelinal sheath.

axon.gif (349 bytes) The axon is the most important section of the neuron. The main purpose of the neuron is to allow a transmission of a message from one cell to another. This transmission would never occur, had there not be the axon. The axon is the long finger like projection of the neural body, the cell body of the neuron. The axon is composed of two principal sections; the axonal ending and the Schwann Cell. The axon is covered by the Myelinal Sheath.

    bullet.GIF (124 bytes) The axonal terminal is the ending of the axonal process. The axonal terminal is also called the neuropodium. The axonal ending is characterized by a bulged ending. The purpose of the axonal terminal is to carry the bulk load of the neurotransmitters. Once the polarized impulse has reached the axonal terminal, a chemical reaction takes place within the axonal terminal. The purpose of the chemical reaction is to release the neurotransmitters.

nuerotransmitter.gif (1012 bytes) Neurotransmitters are chemical substances found within the neuropodium. The purpose of the neurotransmitter is to aid in the transmission of the nervous impulse. The electrical impulse is not capable in diffusing across the synapse. Due to a lacking capabilities of the nervous impulse, a large burden is place on the neurotransmitter. The synapse is the area located between the neurons. Neurons are not connected or closely packed together, as in other tissues of the body. All communication between neurons takes place within the synapse. All nerve impulses must travel across the synaptic gap. The neurotransmitter is the chemical substance which accomplishes the task of crossing the synaptic gap.

dentrite.gif (599 bytes) The dentrite is another section of the neuron which aids in the nervous transmission. The dentrite is one of the many cytoplasmic branches of the neural body. The dentrite aids in transmission by conducting and receiving terminations of neurons. The dentrites are also responsible for receiving impulses from neurotransmitters. Dentrites are characterized as stretching out across the synapse. Dentrites are also known as dentrite processes.

 

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Central Nervous System      Neurons       Peripheral Nervous System

 

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