The Reflex Arc

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The Reflex Arc
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Aim What are the parts of a reflex arc?
I. Reflex involuntary response to a stimulus.
A. Stimulus any change in the environment that
causes a response (reaction). Ex light,
temperature, pressure.
B. Response the action or movement resulting
from a stimulus.
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C. Receptor a specialized nerve tissue that is
sensitive to a specific stimulus.
1. Receptors may be nerve endings in the skin
which may be sensitive to temperature changes.
2. Receptors may be complex organs such as the
eye or ear. Receptors are located in each
sensory organ (eye, ear, tongue, skin, and nose)
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D. Effector part of the body that respond to a
stimulus (muscles or glands).
E. Parts of neuron
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1. Cyton (cell body) contains the nucleus and
decides what the impulse will do (stop or
continue.
2. Dendrites branches off the cyton that
receive impulses from other neurons.
3. Axon part of neuron that takes the impulse
from the cyton towards the terminal branch.
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4. Terminal branch end of the neuron which
takes impulse to next neuron.
II. Parts of a reflex arc
A. Stimulus
B. Receptor
C. Sensory Neuron - carries impulses towards the
spinal cord.
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D. Synapse microscopic gap between the terminal
branch and the dendrite.
E. Interneuron small neuron that lies between a
sensory neuron and a motor neuron. Found in
spinal cord.
F. Motor neuron carries impulses away from the
spinal cord toward the effector.
G. Effector
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