The Nervous System

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The Nervous System
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The Nervous System has 3 Major Functions

• Receives information about the other parts of the
  body
• Interprets the information it receives
• Makes the body respond to this information

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Basic Tasks of the Nervous System
Sensory Input Monitor both external and
internal environments. Integration Process the
information and often integrate it with stored
information. Motor output If necessary, signal
effector organs to make an appropriate response.
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Structure of a Neuron

• The neuron is the basic unit of nervous system

• Electrical impulses are carried throughout the
  body by nerves.

dendrites
are small extensions surrounding the cell body
which receive impulses (0.005 - 0.5mm long)
Is the longest part of the neuron which
propagates the impulse Away from the cell body
(0.5mm to 1m long)
Axon
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The neurons are the only cells that react to a
Stimulus
A stimulus is a change in the environment that
results in nerve excitation.
Example sun shining in your eyes or
hearing a sound
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Basic Parts of Neurons

• Cell body- largest part, contains nucleus and
  cytoplasm, directs the action of the cell
• Axon- long thin fiber (can be coated with myelin)
  extends from cell body and carries these messages
  away from the cells body
• Dendrites- network of tiny branches
• When the impulses reach the end of the axon, they
  come to a small space called a synapse

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NEURON STRUCTURE
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3 TYPES of NEURONS

• A neuron carries information from one location to
  another
• Sensory neurons
• Pick up information from the environment
• Transmit impulses to the spinal cord brain from
  all parts of the body
• Motor neurons
• Transmit impulses away from the brain and spinal
  cord to muscle glandular tissue
• Interneurons
• Conduct impulses from sensory neurons to motor
  neurons

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Neural Impulse

• Self-propagating wave of electrical disturbance
  that travels along the surface of a neurons
  membrane
• Neurotransmitters transport messages across
  synapse

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1) Electrical impulse in axon of presynaptic
neuron causes vesicles to move to terminal
button/axon terminal. 2) Neurotransmitters are
released from the vesicles into the synaptic
cleft
3) Neurotrans- mitters move across synaptic
cleft and bind to specific receptors on
postsynaptic neuron
4) Electrical impulse moves down the dendrite of
the postysynaptic neuron
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Impulse transmitted to next neuron
Neurotransmitter released in synapse
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Central Nervous System
The Central Nervous System is made of the brain
and the spinal cord.
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The BRAIN

• The brain controls everything in the body.

• The brain is made of more than 10 billion
  neurons and is the biggest part of the central
  nervous system!

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Parts of the BRAIN

• The Brain has three main parts

1. The Cerebrum
2. The Cerebellum
3. Medulla oblongata (The Brain Stem)
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The Cerebrum

• The Cerebrum is the largest part of the brain.
  The cerebrum controls your

1. thinking.
2. memory.
3 speaking.
4. movement and identifies the information
gathered by your sense organs.
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The Cerebellum
The cerebellum is below and to the back of
the cerebrum.
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Medulla Oblongata (brain stem)

• The Medulla (Brain Stem) connects the brain to
  the spinal cord.
• The nerves in the brain stem control your
  heartbeat, breathing, and blood pressure.

• Responsible for certain reflexes coughing,
  swallowing, hiccups, vomiting and sneezing

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The Spinal Cord

• The spinal cord is the part of the nervous system
  that connects the brain to the rest of the
  nervous system.
• The spinal cord sends messages to and from the
  brain.

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• The spinal cord is protected by small bones
  called vertebrae

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The Peripheral nervous system

• Consists of all the nerves that leave the spinal
  cord or brain reaching all parts of the body and
  vice-versa.
• It has 2 types of nerves
• Sensory nerves sending info to CNS
• Motor nerves sending info to muscles

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Nerves

• Contain only part of the neuron (the axon)
• motor nerves contain the axons of motor neurons
• Sensory nerves contain the axons of sensory
  neurons

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The involuntary system(Autonomic)

• The medulla oblongata controls this system. The
  bodys activities that you dont think about
  like
• activities in your small intestine, breathing,
  the constriction and dilation of blood vessels
• functioning of organs, liver, kidneys and glands

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The voluntary system(Somatic system)

• This system controls the skeletal muscles
• Responsible for the conscious control of our
  movement
• Signals from the brain effectuate contractions of
  the muscles

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Reflex

• is an involuntary automatic reaction that
  happens without thinking about it.

• A reflex happens quickly in less than a second.

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The brain is not involved in a reflex.
Sensory Receptor (responds to a stimulus by
producing a impulse)
Sensory Neuron (axon conducts impulse)
Integrating Center (Relay impulse from sensory
to motor neurons)
Motor Neuron (axon conducts impulse to effector)
Effector (muscle that responds to A motor nerve
impulse)
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Structure of a Neuron

• The neuron is the basic unit of nervous system

• Electrical impulses are carried throughout the
  body by nerves.

dendrites
are small extensions surrounding the cell body
which receive impulses (0.005 - 0.5mm long)
Is the longest part of the neuron which
propagates the impulse Away from the cell body
(0.5mm to 1m long)
Axon
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Main parts of the Brain
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The brain is not involved in a reflex.
Sensory Receptor (responds to a stimulus by
producing a impulse)
Sensory Neuron (axon conducts impulse)
Integrating Center (Relay impulse from sensory
to motor neurons)
Motor Neuron (axon conducts impulse to effector)
Effector (muscle that responds to A motor nerve
impulse)
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The _____ is ____ involved in a reflex.