Chapter 12 (7)

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  1. What is a stretch reflex?
    Provides automatic regulation of skeletal muscle length.
  2. What are the steps of the patellar reflex?
    • Arrival of stimulus and activation of receptor.
    • Activation of sensory neurons.
    • Information processing in cns.
    • Activation of motor neuron.
    • Response of peripheral receptor.
  3. Describe Muscle spindles.
    • Are sensory receptors of stretch reflex
    • Consist of a bundle of specialized muscle fibers (intrafusal muscle fibers)
    • Are surrounded by larger skeletal muscle fibers responsible for muscle tone and contraction of entire
    • muscle
    • Sensory neuron surrounds muscle spindle and is always sending impulses to CNS through dorsal root
    • Are innervated by gamma motor neurons that alter tension in spindle and control sensitivity of
    • receptor
  4. What are postural reflexes?
    Coordinated activities of opposing muscles to keep body’s weight over feet.
  5. Describe polysynaptic reflexes.
    • Responsible for automatic actions involved in complex movements.
    • May involve sensory and motor responses on the same side of body or opposite sides:
    • -Same side: ipsilateral reflexes
    • -Examples: stretch reflex, withdrawal reflex
    • -Opposite sides: contralateral reflexes
    • -Example: crossed extensor reflex
  6. Describe withdrawl reflexes.
    • Move affected body parts away from stimulus
    • Strongest are triggered by painful stimuli but other stimuli can initiate
    • Show tremendous versatility because sensory neurons activate many pools of interneurons
    • Example: flexor reflex, crossed extensor reflexes
  7. Describe interneurons.
    • Activate motor neurons in anterior gray horn to contract flexor muscles
    • Activated inhibitory interneurons keep extensors relaxed
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Chapter 12 (7)
2012-01-26 01:14:04

Lecture test number one.
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