Download Nervous System

The nervous system is an organ system containing
a network of specialized cells called neurons.
Neurons coordinate the actions of an animal and
transmit signals between different parts of its body.
The nervous system is divided into two main
systems, the central nervous system (CNS) and the
peripheral nervous system.
Think of the brain as a central computer that controls all bodily
functions.
The nervous system then is like the network that relays messages
back and forth from the brain to different parts of the body.
It does this via the spinal cord, which runs from the brain down
through the back and contains threadlike nerves that branch out to
every organ and body part.
The spinal cord and the brain make up the CNS.
Its main job is to get the information from the
body and send out instructions.
It acts as the central control region of the human
nervous system, processing information and issuing
commands.
It contains millions of neurons.
The Peripheral Nervous System consists of all the sensory nerves and
the motor nerves.
Sensory nerves feed information into the spinal cord and brain.
Motor nerves carry messages to other parts of the body from the
brain and spinal cord.
Sensory nerves contain sensory neurons. Motor nerves contain motor
neurons. Mixed nerves contain both sensory and motor neurons.
Sensory neurons are usually connected to motor neurons by
intermediate neurons (sometimes called inter neurones). Sensory,
intermediate and motor nerves have gaps between them
called synapses.
Neurons, are specialized to
carry "messages" through an
electrochemical processes.
Neurons are similar to other cells in the body because:
1.Neurons are surrounded by a cell membrane.
2.Neurons have a nucleus that contains genes.
3.Neurons contain cytoplasm, mitochondria and other organelles.
4.Neurons carry out basic cellular processes such as protein synthesis
and energy production.
Neurons differ from other cells in the body because:
1.Neurons have specialized extensions called dendrites and axons.
2.Dendrites bring information to the cell body and axons take
information away from the cell body.
3.Neurons communicate with each other through an electrochemical
process.
4.Neurons contain some specialized structures (for example, synapses)
and chemicals (for example, neurotransmitters).
When a message comes to the Brain from anywhere in the body
the Brain tells the body how to react.
Let’s say you accidently touch a hot stove. The sensory nerves in
your skin send a message to your brain. Your brain sends a
message back to the muscles in your hand telling it to move.
Luckily this message passing takes no time at all.
Considering all the things that your brain does, it is incredibly
small and compact. It only weighs about three pounds. It has extra
folds and grooves that provide it with more surface area to store
inforamtion.
The Brain is made up of 3 major parts: The Forebrain, The Midbrain and
The Hindbrain
The Forebrain:
Largest and most complex
Contains the cerebrum
The cerebrum contains the parts that make us who we are- our
intelligence, memory, personality, emotion, speech, and ability to feel and
move.
Specific areas of the cerebrum are in charge of controlling each of these
things. These areas are called lobes. There are four main lobes: frontal,
parietal, temporal, and occipital.
The Midbrain:
located underneath the middle of the forebrain
Acts as a master coordinator for all the messages going in and out of the
brain to the spinal cord.
The Hindbrain:
sits underneath the back end of the cerebrum
responsible for balance, movement, and coordination.
The spinal cord is the main pathway for information connecting the brain
and peripheral nervous system.
The human spinal cord is protected by the bony spinal column shown to
the left.
The spinal column is made up of bones called vertebrae.
Although the spinal column is somewhat flexible, some of the vertebrae
in the lower parts of the spinal column become fused.