The Nervous System

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The Nervous System

• Neurons, Nerves, the Brain and Neurotransmitters

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Organization of the nervous system
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The central nervous system

• The Brain Spinal Cord
• Spinal cord A collection of neurons and
  supportive tissue running from the base of the
  brain down the center of the back
• Protected by spinal column

But the central nervous system is only one part
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Spinal Reflexes Who Needs a Brain?

• For example, pulling your hand away from
  something hot
• No need to involve the brain
• Spinal reflexes go right from the skin to the
  spinal cord back to the muscle
• Neurons that serve the skin and muscles in arms
  and legs are part of the peripheral nervous
  system
• So, spinal reflexes involve the central and
  peripheral nervous systems

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Organization of the nervous system
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Peripheral Nervous System

• 43 pairs of nerves
• Nerves are bundles of many, many neurons
• 12 pairs go straight to the brain
• 31 pairs go to the spinal cord (remember the
  spinal reflexes?)

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Peripheral Nervous System

• Autonomic (think automatic) controls heart,
  stomach, etc.
• Somatic Arms and legs things you control
  voluntarily

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Autonomic Nervous System

• Sympathetic Prepares the body for ACTION!
• Parasympathetic Rests the body and restores to
  get ready for next round.

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Organization of the nervous system
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A Neuron is a very special cell You have about
100 billion of them!

• Dendrites Receive information from other neurons
  and transmit toward the cell body

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A Neuron is a very special cell You have about
100 billion of them!

• Cell body Keeps the neuron alive and determines
  whether it will fire
• AxonExtending fiber that conducts impulses away
  from the cell body and transmits to other cells.

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Neurotransmitter

• Chemical released by a transmitting neuron at the
  synapse and capable of affecting the activity of
  a receiving neuron

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Major neurotransmitters
Serotonin involved in treatment of
depression Dopamine Acetylcholine
(Ach) Norepinephrine Gamma aminobutyric acid
(GABA) Glutamate Endorphins runners high
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The brain stem

• Pons Involved in sleeping, waking, and dreaming

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The brain stem
chapter 4

• Medulla Responsible for certain automatic
  functions such as breathing and heart rate

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The brain stem
chapter 4

• Reticular activating system Arouses cortex and
  screens incoming information

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The cerebral cortex curly