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Human Nervous System
The Human Nervous System is made up of a complex network of specialised nerve cells known as neurons. Neurons
are the building blocks of the nervous system and are responsible for communicating messages throughout the
body. At birth, the human brain consists of an estimated 100 billion neurons. Each firing off 5–50 messages or
signals per second. If you touch something hot, that information goes from your fingertips to your brain, and then
your brain says “move your hand away otherwise it will burn!” and sends information to your fingertips telling
them to move away.
A neuron is made up of a cell body, an axon and dendrites. The cell body has genetic information, maintains the
neuron’s structure, and provides energy during the transmission of signals.
An axon is an elongated structure which joins the cell body. Dendrites are fibrous roots that branch out from the cell
body.
There are three types of neurons in our body:
• Sensory neuron: It carries the sensory signals from sensory organs to the brain. It gets activated when you
touch, smell, hear, see or feel something.
• Motor Neuron: It carries the signal from the brain or spinal cord to the organs, glands or muscles to carry out
voluntary or involuntary movement.
• Interneuron: They connect the sensory and motor neurons to help in the transmission of signals and form a
complex internal neuron network.
During the transmission, the nerve impulse travels in the form of electrical signals from the axon of one neuron
to another neuron through a joint called synapse. The dendrites of another neuron receives an impulse which
travels through the cell body and performs an activation function on the impulse received and then gives it to
the output axon which passes the same to the next neuron in the system.
Dendrites
Soma
Nucleus
Axon hillock
Myelin sheath
Schwann cell
Node of ranvier
Terminal
button
A nerve cell (neuron)
Relation between the Neural Network and Nervous System
Just like the human brain where all neurons are interconnected to one another, artificial neural networks also
have a large number of artificial neurons(nodes) that are interconnected to one another in a sequence of layers
of the networks.
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