The Nervous System
Your nervous system is the most complex system
in your body – much of which is still a mystery
to us. Your nervous system is what controls
your whole body and also manages all of your
intellectual activities such as memory, choice and
emotions. The nervous system consists of the
brain, spinal cord, sensory organs and all of the
nerves which connect to the rest of the body. The
central nervous system consists of the brain and
spinal cord and the peripheral nervous system
consists of the sense organs and sensory nerves.
The Central Nervous System (CNS)
The Peripheral Nervous System (PNS)
Your brain consists of a cerebrum, cerebellum
and spinal bulb. Your spinal cord along with your
brain receives information from your sense organs
and sends out instructions to all of your muscles
and other organs. The central nervous system is
also responsible for processing and coordinating
nervous signals that are transmitted from the
peripheral nervous system.
The peripheral nervous system provides
information to the central nervous system and also
coordinates your movement. It informs your CNS
about external changes detected by your senses
and internal changes such as having a full bladder.
It sends instructions for your conscious movement
such as walking, sitting, running and also controls
the functioning of your internal organs.
Neurons
Cells of the nervous system are called neurons.
They transmit impulses in the form of electrical
signals and carry information to the brain.
Your brain has around 100 billion neurons
that come in many different shapes and sizes.
Each neuron in your brain can be connected
with several thousand other neurons and can
receive up to 100,000 signals a second. They
are similar to other cells in your body in many
ways, but they are also very different. Neurons
have special cell parts called dendrites and
axons. Dendrites are the branches through
which a neuron receives signals from other
neurons. There can be around 200 dendrites
per neuron, but this varies. The axon is the
nerve fibre that transmits impulses.
There are three main types
of neurons, based on how
complicated their axons and
dendrites are:
1. Unipolar
These have two branches of
the same axon that extend
from one cell body
2. Bipolar
These neurons have two
completely separate axons
that extend from each end
of a cell body
3. Multipolar
These have one axon with
a number of dendrites
extending from a cell body.
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