STRUCTURE OF NEURON AND ITS TYPES

1. NEURON
PRESENTED BY: Ms. SUKHRAJ KAUR
M.Sc. NURSING (PEDIATRICS)
ASHOKA INSTITUTE OF NURSING, PATIALA

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 Neurons are the cells considered to be the
structural and functional unit of the nervous
system.
 They are responsible for the electrical
signals that communicate information about
sensations, and that produce movements in
response to those stimuli, along with
inducing thought processes within the brain.
 An important part of the function of neurons
is in their structure, or shape.

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 Cell body
 Dendrites
 Axon
 Axon terminal


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 The main portion of the
neuron is called cell
body.
 In the center of the cell
body is the nucleus of
the cell, where the
chromosomes that
contain all of the genetic
material are stored.

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Conti..
 This is also the part of the cell that
creates mRNA for cell replication.
 The cell body relays the information
down to the axon

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DENDRITES
 Dendrites are branch-like structures
extending away from the cell body, and
their job is to receive messages from
other neurons and allow those messages
to travel to the cell body.
 Dendrites are specialized to receive
signals from neighboring neurons and
carry them back to the cell body

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It is a tube-like structure that carries
an electrical impulse from the cell
body to the structures at opposite
end of the neuron i.e axon terminals,
which can then pass the impulse to
another neuron.

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 Myelin sheath is also present around the
axons is called as myelinated nerve
fibers.
 This myelin sheath further consist of
protein- lipid complex called as schwann
cells.
 There is a short gap between the two
segments of axon is the Nodes of
Ranvier where the signals get recharged

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AXON TERMINAL
An Axon terminal is the very end of a
branch of nerve axon. Axon Terminal
is the last step for the relay of
information inside the neuron.

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-Electrical Communication
-Chemical Communication
How do Neurons Communicate?

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 Action potential is an electrical current
sent down the axon.
 The activity within the neurons is
electrical. This current causes the
neuron to “fire”

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Action potentials travel down the axon
like a wave of energy

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 The Synapse is the space Or synaptic gap
between neurons
• Information must be transmitted across the
synapse to other neurons via the
neurotransmitters.
• This is an electrochemical process

17. Let’s Review!

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 Neurotransmitters are chemical substances
that reside in the axon terminals
• They communicate to other neurons by
binding to receptors on neighboring
neurons

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 The communication between neurons
is chemical

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TYPES OF NEURONS
There are many neurons in the nervous
system—a number in the trillions.
They can be classified as:
 Depending upon the number of poles
1. Unipolar Neurons
2. Bipolar Neurons
3. Multipolar Neurons

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 Depending upon the functions
1. Motor neurons
2. Sensory neurons

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Depending upon the number of poles

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1. Unipolar Neurons
 These neurons have a single pole,
from which the both axon and
dendrites arise.
 True unipolar are present only in
embryonic stage in human being.

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2. Bipolar Neurons
 These neurons have two poles, one
for axon & other for dendrite.
 Bipolor neurons are found in the
vestibular, cochlear ganglia, in the
nasal olfactory epithelium & bipolar
cells in the retina of the eye.

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3. Multipolar Neurons
 These have many poles.
 One of the pole gives rise to axon
and all other to dendrites.
 In CNS most of the neurons are
multipolar.

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Depending upon the functions
1. Motor neurons
 These are also known as efferent
nerve cells.
 These carry impulses from CNS to
the effector organ like muscles,
glands, blood vessels.
 These neurons have very long axon
and short dendrites.

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2. Sensory neurons
 These are also known as afferent
nerve cells.
 These carry impulses from effector
to the CNS.
 These neurons have very short
axon and long dendrites.