What is Nerve cells? Types of Nerve cells:

 What is Nerve cells?

            Nerve cells or neurons are the structural and functional units of the nervous system.

            The Human Brain is made up of about 86 billion neurons and many more neuroglial cells (more than 86 billion). A nerve cell is a microscopic structure consisting of three major parts namely, cell body, dendrites and axon.

Nerve cells

Types of Nerve cell:

•     Myelinated or Medullated or White neurons:

                    When the axon is enclosed by the white fatty myelin cover, it is called Myelinated or Medullated or White neurons.  This forms the white matter of our brain.

•     Non-Myelinated or Non-Medullated or Grey neurons:

                    This neuron is not enclosed by the myelin sheath; so it appears greyish in colour.  The axon is covered only by neurilemma and Schwann cells.  This type of neuron is found in the grey matter of cerebrum.

•     Unipolar neurons:

                    The developing embryonic nervous tissue contains unipolar neurons.  A unipolar neuron has a nerve cell body with a single process or fibre, which acts both as axon and dendron.

Nerve cells

•     Bipolar neurons:

                    The sensory hair cells of the sense organs like rods and cones of retina are made up of bipolar neurons.  Each bipolar neuron has a cell body and two processes at the ends, one acting as axon and the other acting as dendron.

•     Multipolar neuron:

                    The cerebral cortex contains multipolar neurons.  Each multipolar neuron has a cell body with many dendrites and a axon.