Neurons are the basic building blocks of the nervous system and specialized to transmit information throughout the body chemically and electrically. They have a cell body that receives signals from dendrites and transmits signals down the axon via an axon hillock. At the end of the axon are terminal buttons that release neurotransmitters across synapses to communicate with other neurons. There are three main types of neurons - sensory, motor, and interneurons.

1. PsychobiologyPsychobiology
Cells of the NervousCells of the Nervous
Syed Md. Sajjad KabirSyed Md. Sajjad Kabir
Lecturer, Dept. of Psychology, CULecturer, Dept. of Psychology, CU
AnatomyAnatomy
of Neuronsof Neurons
SupportiveSupportive
Cells of NSCells of NS

2. What is a Neuron?What is a Neuron?
 A neuron is a nerve cell that is the basicA neuron is a nerve cell that is the basic
building block of the nervous system.building block of the nervous system.
 Neurons are specialized to transmitNeurons are specialized to transmit
information throughout the body.information throughout the body.
 Nerve cells are responsible forNerve cells are responsible for
communicating information in bothcommunicating information in both
chemical and electrical forms.chemical and electrical forms.
 While neurons do not reproduce,While neurons do not reproduce,
research has shown that new connectionsresearch has shown that new connections
between neurons form throughout life.between neurons form throughout life.

3. What is a Neuron?What is a Neuron?
 Neurons have a membrane that isNeurons have a membrane that is
designed to sends information to otherdesigned to sends information to other
cells.cells.
 The axon and dendrites areThe axon and dendrites are
specialized structures designed tospecialized structures designed to
transmit and receive information.transmit and receive information.
 The connections between cells areThe connections between cells are
known as a synapses.known as a synapses.
 Neurons release chemicals known asNeurons release chemicals known as
neurotransmitters into these synapsesneurotransmitters into these synapses
to communicate with other neurons.to communicate with other neurons.

4. Types of NeuronsTypes of Neurons
 Sensory neurons carry information from theSensory neurons carry information from the
sensory receptor cells throughout the body to thesensory receptor cells throughout the body to the
brain.brain.
 Motor neurons transmit information from the brainMotor neurons transmit information from the brain
to the muscles of the body.to the muscles of the body.
 Interneurons are responsible for communicatingInterneurons are responsible for communicating
information between different neurons in the body.information between different neurons in the body.
 3 types - all with cell body & processes (axons &3 types - all with cell body & processes (axons &
dendrites)dendrites)
 MultipolarMultipolar
 BipolarBipolar
 UnipolarUnipolar

5. Structure of a NeuronStructure of a Neuron
Three basic parts of a neuron: the dendrites, the cell body, and the axon.Three basic parts of a neuron: the dendrites, the cell body, and the axon.
However, all neurons vary somewhat in size, shape, and characteristics dependingHowever, all neurons vary somewhat in size, shape, and characteristics depending
on the function and role of the neuron.on the function and role of the neuron.
Some neurons have few dendritic branches, while others are highly branched inSome neurons have few dendritic branches, while others are highly branched in
order to receive a great deal of information.order to receive a great deal of information.
Some neurons have short axons, while others can be quite long. The longest axon inSome neurons have short axons, while others can be quite long. The longest axon in
the human body extends from the bottom of the spine to the big toe and averages athe human body extends from the bottom of the spine to the big toe and averages a
length of approximately three feet!length of approximately three feet!
Figure: The Structure of a NeuronFigure: The Structure of a Neuron

6. Structure of a Neuron
Dendrites are treelike extensions at the beginning of a neuronDendrites are treelike extensions at the beginning of a neuron
that help increase the surface area of the cell body and arethat help increase the surface area of the cell body and are
covered with synapses.covered with synapses.
These tiny protrusions receive information from other neuronsThese tiny protrusions receive information from other neurons
and transmit electrical stimulation to the soma.and transmit electrical stimulation to the soma.
Most neurons have many dendrites.Most neurons have many dendrites.
Short and highly branched.Short and highly branched.
Transmits information to the cell body.Transmits information to the cell body.
DendritesDendrites

7. Structure of a Neuron
The soma is where the signals from the dendrites are joined and passedThe soma is where the signals from the dendrites are joined and passed
on.on.
The soma and the nucleus do not play an active role in the transmission ofThe soma and the nucleus do not play an active role in the transmission of
the neural signal. Instead, these two structures serve to maintain the cellthe neural signal. Instead, these two structures serve to maintain the cell
and keep the neuron functional.and keep the neuron functional.
The support structures of the cell include mitochondria, which provideThe support structures of the cell include mitochondria, which provide
energy for the cell, and the Golgi apparatus, which packages productsenergy for the cell, and the Golgi apparatus, which packages products
created by the cell and secretes them outside the cell wall.created by the cell and secretes them outside the cell wall.
SomaSoma

8. Structure of a Neuron
The axon hillock is located and the end of the soma andThe axon hillock is located and the end of the soma and
controls the firing of the neuron.controls the firing of the neuron.
If the total strength of the signal exceeds the threshold limitIf the total strength of the signal exceeds the threshold limit
of the axon hillock, the structure will fire a signal down theof the axon hillock, the structure will fire a signal down the
axon.axon.
Axon HillockAxon Hillock

9. Structure of a Neuron
The axon is the elongated fiber that extends from the cell body to theThe axon is the elongated fiber that extends from the cell body to the
terminal endings and transmits the neural signal.terminal endings and transmits the neural signal.
The larger the axon, the faster it transmits information.The larger the axon, the faster it transmits information.
Some axons are covered with a fatty substance called myelin thatSome axons are covered with a fatty substance called myelin that
acts as an insulator. These myelinated axons transmit informationacts as an insulator. These myelinated axons transmit information
much faster than other neurons.much faster than other neurons.
AxonAxon

10. Structure of a Neuron
The terminal buttons are located at the end of the neuronThe terminal buttons are located at the end of the neuron
and are responsible for sending the signal on to other neurons.and are responsible for sending the signal on to other neurons.
At the end of the terminal button is a gap known as aAt the end of the terminal button is a gap known as a
synapsesynapse..
Neurotransmitters are used to carry the signal across theNeurotransmitters are used to carry the signal across the
synapse to other neurons.synapse to other neurons.
Terminal ButtonsTerminal Buttons