This slide describes the neurons and their types. Neurons are connected to cognitive science in education and other science fields.

1. NEURONS & TYPES
By
Dr.S.Jerslin

2. NEURONS
 Neuron Definition
 “Neurons are the fundamental unit of the nervous system
specialized to transmit information to different parts of
the body.”
 Neurons, also known as nerve cells, send and receive signals
from your brain. While neurons have a lot in common with
other types of cells, they’re structurally and functionally
unique.
 Specialized projections called axons allow neurons to transmit
electrical and chemical signals to other cells. Neurons can
also receive these signals via rootlike extensions known as
dendrites.
 What Is a Neuron? Diagrams, Types, Function, and More
 https://www.healthline.com › health › neurons

3. Con…
 A 2009 study estimated that the human brain houses
about 86 billion neuronsTrusted Source. The
creation of new nerve cells is called neurogenesis.
While this process isn’t well understood, we know
that it’s much more active when you’re an embryo.
However, 2013 evidenceTrusted Source suggests
that some neurogenesis occurs in adult brains
throughout our lives.
 As researchers gain insight into both neurons and
neurogenesis, many are also working to uncover
links to neurodegenerative diseases such
as Alzheimer’s and Parkinson’s.

4. DIAGRAM

5. Parts of a neuron
 Neurons vary in size, shape, and structure depending on
their role and location. However, nearly all neurons have
three essential parts: a cell body, an axon, and dendrites.
 Cell body
 Also known as a soma, the cell body is the core section
of the neuron. The cell body contains genetic information,
maintains the neuron’s structure, and provides energy to
drive activities.
 Like other cell bodies, a neuron’s soma contains a
nucleus and specialized organelles. It’s enclosed by a
membrane that both protects it and allows it to interact
with its immediate surroundings.

6. Con…
 Axon
 An axon is a long, tail-like structure. It joins the cell body at a
specialized junction called the axon hillock. Many axons are
insulated with a fatty substance called myelin. Myelin helps
axons to conduct an electrical signal.
 Neurons usually have one main axon.
 Dendrites
 Dendrites are fibrous roots that branch out from the cell body.
Like antennae, dendrites receive and process signals from the
axons of other neurons. Neurons can have more than one set
of dendrites, known as dendritic trees.
 How many they have generally depends on their role. For
instance, Purkinje cells are a special type of neuron found in a
part of the brain called the cerebellum. These cells have highly
developed dendritic trees which allow them to receive
thousands of signals.

8.  Types of Neurons: Parts, Structure, and Function - Verywell ...
 https://www.verywellhealth.com › types-of-neurons-52...
 What Is a Neuron? - Definition, Structure, Parts and Function
 https://byjus.com › Biology › Biology Article
 Neuron (Nerve Cell) Types, Structure and Function - Simply ...
 https://www.simplypsychology.org › neuron
 Neurons | Boundless Psychology - Lumen Learning
 https://courses.lumenlearning.com › chapter › neurons

9. TYPES OF NEURONS
 There are many different types of neurons, and they
all have special functions in the brain, spinal cord,
and muscles that control our body. These different
types of neurons are highly specialized. Some
neurons are responsible for taste while others sense
pain.
 Traditionally, scientists classify neurons based on
function into three broad types:
 Sensory Neurons
 Motor Neurons
 Interneurons

10. Con…
 Scientists also classify neurons into four groups
based on structural differences:
 Multipolar
 Unipolar
 Bipolar
 Pseudo-unipolar

11. Sensory Neurons
 Sensory neurons help you:
 taste
 smell
 hear
 see
 feel things around you
 Sensory neurons are triggered by physical and
chemical inputs from your environment. Sound, touch,
heat, and light are physical inputs. Smell and taste are
chemical inputs.
 For example, stepping on hot sand activates sensory
neurons in the soles of your feet. Those neurons send a
message to your brain, which makes you aware of the
heat.

12. Motor Neurons
 Motor neurons play a role in movement, including
voluntary and involuntary movements. These neurons
allow the brain and spinal cord to communicate with
muscles, organs, and glands all over the body.
 There are two types of motor neurons: lower and upper.
Lower motor neurons carry signals from the spinal cord
to the smooth muscles and skeletal muscles. Upper
motor neurons carry signals between your brain and
spinal cord.
 When you eat, for instance, lower motor neurons in your
spinal cord send signals to the smooth muscles in your
esophagus, stomach, and intestines. These muscles
contract, which allows food to move through your
digestive tract.

13. Interneurons
 Interneurons are neural intermediaries found in
your brain and spinal cord. They’re the most
common type of neuron. They pass signals from
sensory neurons and other interneurons to motor
neurons and other interneurons. Often, they form
complex circuits that help you to react to external
stimuli.
 For instance, when you touch something sharp like a
cactus, sensory neurons in your fingertips send a
signal to interneurons in your spinal cord. Some
interneurons pass the signal on to motor neurons in
your hand, which allows you to move your hand
away. Other interneurons send a signal to the pain
center in your brain, and you experience pain.

14. Types of neurons based on structure
include:
 Unipolar neurons: These neurons have a single long axon
that is responsible for sending electrical signals. The axon in
unipolar neurons is myelinated, which allows for rapid signal
transmission.
 Multipolar neurons: These neurons are able to receive
impulses from multiple neurons via dendrites. The dendrites
transmit the signals through the neuron via an electrical signal
that is spread down the axon.
 Bipolar neurons: These neurons send signals and receive
information from the world. Examples include the neurons in
the eye that receive light and then transmit signals to the
brain.
 Pseudo-unipolar neurons: These neurons relay signals
from the skin and muscles to the spinal cord. They are the
primary neurons responsible for coordinating movement of the
arms and legs using input from the brain.

15. DIAGRAM

16. How do neurons work?
 Synapses are locations where neurons can pass
these electrical and chemical messages between
them. Synapses are made up of a presynaptic
ending, a synaptic cleft, and a postsynaptic
ending. Action potentials can trigger both
chemical and electrical synapses.
 Neurons send signals using action potentials. An
action potential is a shift in the neuron’s
potential electric energy caused by the flow of
charged particles in and out of the membrane of the
neuron. When an action potential is generated, it’s
carried along the axon to a presynaptic ending.

17. Chemical synapses
 In a chemical synapse, the neuron releases of
chemical messengers called neurotransmitters.
These molecules cross the synaptic cleft and bind to
receptors in the postsynaptic ending of a dendrite.
 Neurotransmitters can trigger a response in the
postsynaptic neuron, causing it to generate an action
potential of its own. Alternatively, they can prevent
activity in the postsynaptic neuron. In that case, the
postsynaptic neuron doesn’t generate an action
potential.

18. Electrical synapses
 Electrical synapses can only excite. These synapses
form when two neurons are connected by a gap junction.
This gap is much smaller than a chemical synapse and is
made up of ion channels that help transmit a positive
electrical signal.
 Because of the way these signals travel, signals move
much faster across electrical synapses than
chemical synapses. However, these signals can
diminish from one neuron to the next. This makes them
less effective at transmitting repeated signals.
 Types of Neurons: Parts, Structure, and Function -
Verywell ...
 https://www.verywellhealth.com › types-of-neurons-52...

19. DIAGRAM

20. TYPES-NATURE OF CONECTION
 Based on the nature of connections, synapses are
classified into 3 types
 1. Axo-somatic synapse
 2. Axo-dentritic synapse
 3. Axo-axonic synapse
 1. Axo-Somatic-AXON ends in soma of another
neuron.
 2. Axo-dentritic-Axon ends on dentritics of another
neuron
 3. Axo-axonic- Axon ends in axon of another neuron.

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