How is your nervous system like a computer?

1
How is your nervous system like a computer?
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There are four primary functions of the nervous
system

• Sensing the world
• Vision, Hearing, Smell, Taste, Touch
• Transmitting information
• Processing information
• Producing a response

3
The evolution of the nervous system reflects
increasing complexity and centralized control

• All animals except sponges have nervous system
  tissue
• The most basic nervous system is the nerve net
  (e.g. Hydra)
• Increasing centralized control (ganglia) is
  evident in worms and insects (e.g. leech)
• Fish, birds and mammals have evolved a central
  control center, the brain

4
The human nervous system can be divided into two
components

• The central nervous system
• Brain and Spinal cord
• The peripheral nervous system
• Any nervous tissue not contained within bone
• Composed of the sympathetic and parasympathetic
  divisions

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The nervous system is composed of two basic types
of cells

• Neurons
• The communication mechanisms
• Three types Sensory, Inter-neuron, Motor

• Glial cells
• The support mechanisms
• Provide myelin (oligodendrocytes, Schwann cells)
• Bring nutrients (astrocytes)
• Remove damaged cells (microglia)

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Each part of a neuron has a particular function

• Dendrites - input
• Cell body (Soma)- integration
• Axon - output

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Neurons are always ready to send information

• An inactive neuron is at its resting potential
• The resting potential is due to more negatively
  charged ions inside the cell (intracellular Cl-,
  Anions(-), K) compared to outside the cell
  (extracellular Na)

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When a neuron is stimulated, it may send an
action potential (nerve impulse) to the next cell
in a circuit

• During the action potential, the charge across
  the cell membrane reverses, making the inside of
  the neuron positive due to the positive ions
  (Na) moving from the extracellular space to the
  inside of the cell
• The cell returns to the resting potential when
  K ions move to the extracellular space

Animation
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The action potential moves down the length of the
axon in one direction
The action potential moves in one direction
because the membrane is refractory (unable to
respond) once the action potential has been
initiated at any particular place on the membrane
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The action potential initiates a chemical process
at the synapse

• Neurotransmitters are released into the synapse
  between neurons when an action potential reaches
  the end of the axon
• There are many different neurotransmitters in
  the nervous system
• Each neuron produces only one type of
  neurotransmitter

Animation
11
The reflex arc illustrates information flow in
the nervous system

• Reflexes are automatic. You do not have control
  over whether they happen, but you may be able to
  control how strong they are.

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Functional Neuroanatomy

• What does localization of function mean in the
  nervous system?

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Functions are well organized in the central
nervous system
Organization of the nervous system begins in the
spinal cord
Peripheral N.S. Dermatome Reflexes Pattern
generation
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The reflex arc illustrates information flow in
the nervous system

• Reflexes are automatic. You do not have control
  over whether they happen, but you may be able to
  control how strong they are.

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The anatomy and function of the brain can be best
understood in 3 dimensions
This is the middle of your brain
This is the side of your brain
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The brainstem controls basic life functions
Heart-rate, breathing and control of other
internal organs is controlled here. Damage here
will usually kill you.
Coma Cranial nerves Pupil function Fight or
Flight
Medulla
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The Limbic System controls your emotions and
memories
Damage to these areas of the brain can lead to
amnesia or emotional disturbances
Declarative amnesias Partial seizures Attention
deficits Fear/Aggression
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The basal ganglia and cerebellum control movement
and output from the brain
The basal ganglia put movements in order and the
cerebellum makes them happen at the right time
Sequence and Timing Eye movements Motor
tasks Procedural amnesia balance and
coordination Parkinsons Disease Huntingtons
Chorea Ataxia
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The cortex is where anything you experience
and/or learn is stored
There are four main lobes of the cortex, each
with different functions
Parietal Sense of Space Touch
Frontal Movement Planning and decisions
Temporal Declarative Memory Hearing Emotion
Occipital Vision
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The sensory and motor homunculi are a perfect
example of functional organization in the nervous
system
Little man Homonculus