Answer:
The correct order would be
Sensory receptors in the arteries detect low oxygen levels.
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Sensory neurons generate an impulse.
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The central nervous system relays an impulse to certain brain regions.
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The brain sends signals through motor neurons.
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Isabel's breathing rate increases.
The working of the nervous system can be summarized as:
The receptors receives the stimulus which then send signals to the brain with the help of sensory neurons.
For example, sensory receptors in the arteries detect the low oxygen levels after which sensory neurons send the signals to the brain.
The stimulus or information is processed in a specified region of the brain which then sends the signals to the effector organ via motor neurons.
The action or reaction is generated at the effector site such as an increase in the breathing rate of Isabel in this case.