The nervous system is essentially made of a large number of nerve cells. The nerve cell is the structural unit the nervous system. It is known as the neuron or nerve cells, which form the functional units of the nervous system.
Neurons are cells that are the integrating units of the nervous system, and although they share many of the characteristics of other cells in the body they have special characteristics that make them particularly adaptable to their functions.
Neurons are modifiable, they change their behavior with experience; they learn, they remember; and they forget. At times neurons can enclosed in a specialized membrane and consists of a cell body, processes called dendrites (from the Greek, meaning tree) a process called an axon (from the Greek, meaning axle) and little end feet on the terminal branches of the axon. The dendrites collect information, which is then integrated at the axon hillock close to the cell body; a summary of the input received by the cell is then passed long the axon, through the end feet to other cells.
STRUCTURE OF NEURON
Part 1- Cell Body in Neuron
All neurons are certain to have a cell body or soma.it contains the nucleus of the cell which contains the genetic information that keep the cell functioning. With nucleus it contains the cytoplasm that sustains the cell’s life. The soma combines and averages all the information coming in from its dendrites and passes it to an extended fiber, the axon.
Soma, often circular in shape, furnishes the cell with nutrients and manufactures chemicals used in transmitting information.
Part 2- What is the Dendrites?
It is derived from Geek word meaning tree. Dendrites are the branch like extensions from a neuron’s cell body where most neural impulses are received. In a mature neuron, there may be thousands of dendrites. Typically dendrites reach out to receive messages, called neural impulses from other neurons.
Part 3- What is Axon & its Function?
It is a long tube like extension of a neuron. It carries an impulse away from the cell body toward the synapse. Axons take the signal from soma and conduct it along its length. This length varies; it can be more than three feet in the spinal cord and less than a millimeter in brain.
Axons end in swollen, bulb like structures called terminal buttons. These provide the mechanism for getting the signals across from the axon of one neuron to the dendrites or soma of neighboring neuron. Neurons transmit information in only one direction according to the law of forward conduction, from the axon of one neuron to the dendrites or cell bodies of the next.
MYELIN SHEATH
It is a white fatty covering found on some axons that serve to insulate and protect them while increasing the speed of impulse.
Actually neurons are covered with glial cells. They do not conduct information as neurons, but they have three important functions, i.e., garbage removal, insulation and poison control. When neurons are damaged or dead glial cells in the area multiply and clean up the cellular junk left behind.
Second function in vertebrate brain is to form an insulating covers called myelin sheath around the large axons. Special glial cells wrap themselves around the axons as the nervous system of the embryo develops. The fatty insulator greatly increases the speed of nerve signal conduction. Third function of glial is to prevent poisonous substance in the blood from reaching the delicate cells of the brain.
