Nerve Cells

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Nerve Cells

• The Neuron

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Fun facts about neurons

• Most specialized cell in animals
• Longest cell
• blue whale neuron
• 10-30 meters
• giraffe axon
• 5 meters
• human neuron
• 1-2 meters

Nervous system allows for 1 millisecond response
time
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3 parts of a Neuron

• Dendrite branched end that extends out from the
  cell, provides a large surface area to receive
  nervous information
• Cell Body integration center, find regular cell
  organelles (nucleus etc)
• Axon long thin fiber, extends out from cell
  body, carries action potential from cell body
• -ending are called synaptic terminals

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Nervous system cells

• Neuron
• a nerve cell

signal direction
dendrites

• Structure and function
• many entry points for signal
• one path out
• transmits signal

cell body
axon
signal direction
synapse
dendrite ? cell body ? axon
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3 Types of Neurons

1. Motor connects to a muscle or gland
2. Sensory receives a stimulus
3. Interneuron connects the above 2

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Reflex

• Rapid, predictable, and involuntary responses to
  stimuli

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Reflex arc

• Direct nervous message from a sensory neuron to
  inter-neuron to a motor neuron to an effector (a
  muscle or a gland)

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Reflex Arc

• A motor, sensory and inter neuron form a reflex
  arc
• Begins with a stimulus causing an impulse in the
  sensory receptors of a sensory neuron.
• The impulse then continues on through the
  dendrite, cell body and axon of a sensory neuron.

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• The impulse passes to the interneuron, passing
  through dendrite, cell body and axon.
• The impulse passes onto the motor neuron, which
  causes a response in an effector (a muscle or a
  gland)

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