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UNIT THREE
Spinal cord
Cell body of
motor neuron
Axon of motor
neuron
Axon of sensory
neuron
Cell body of
sensory neuron
Receptor associated with
dendrites of sensory neuron
Effector (quadriceps femoris
muscle group)
Patella
Patellar ligament
Direction of impulse
Interneuron
Spinal cord
Cell body of
motor neuron
Axon of sensory neuron
Cell body of sensory neuron
Dendrite of
sensory
neuron
Direction
of impulse
Axon of
motor neuron
Effector (flexor
muscle contracts
and withdraws part
being stimulated)
Pain
receptor
in skin
Tack
FIGURE 11.9
A withdrawal ref
ex involves a sensory neuron, an interneuron, and a motor neuron.
FIGURE 11.8
The patellar ref
ex involves two neurons—a sensory
neuron and a motor neuron. Note the single synapse in the spinal cord.
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