What is Neuron, its structure and function
Neuron is
special kind of animal cell which can generate and conduct electric current. In
order to understand the way of generating electric signals, we study its
structure.
Structure of
neuron:
Neurons differ
considerably in size and shape but generally differentiated into following
three regions: Soma, dendrites and axon. Soma is also called cell body. It
contains cytoplasm and nucleus. In addition to typical cell organelles, it
contains Nissl substance which consists of ribosomes. From soma arises a number
of thread like processes the dendrites which receive stimuli and convey it to
soma.
Axon is long
cytoplasmic process which usually arises opposite to dendrites. It is the
conducting end of a neuron. It ends in knob like structures, the axon
terminals. It originates from a pyramid like area of soma called axon hillock.
The axons of some neurons are covered by a myelin sheath.
Types of Neuron:
Functionally
neurons can be differentiated into following three types.
(i) Sensory
neuron: It carries sensory information from the receptor to other neurons or
directly to CNS.
(ii) Motor
neuron: It takes commands of the control centre to the effector.
(iii) Inter
neuron: They are found in central nervous system. Depending upon the presence
or absence of myelin sheath, neurons are called myelinated and un myelinated
neuron respectively.
Functions of
Neuron:
Neuron is a
functional unit of nervous system. It is involved in communication by receiving
stimuli, integrating various stimuli and sending appropriate instructions to
some of the effector organs.
Neuroglia (Glial
cells):
Neurons in
central nervous system (CNS) are associated with another type of cells called
neuroglia. These smaller separate neurons from one another, from myeline sheath
and are also involved in trophic and phagocytic functions. They occur in
several structural and functional types.
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