Stimulus Response/Reflex Action

·  Sensory Neurons Detect a Stimulus

• Sensory neurons pick up signals from any of the five senses.

• Example: When Mrs. Page screamed, it stimulated ear neurons, and jumping on the table stimulated eye neurons.

·  Nerve/Electrical Impulses Travel to the Spinal Cord

• The electrical impulses (not the actual stimulus) travel through the nerves to the spinal cord.

·  Impulses Travel from the Spinal Cord to Muscle Neurons

• The spinal cord sends electrical impulses to the muscle neurons, causing the muscles to react/contract.

• Example: Most of us jumped, our bodies tensed, heart rates increased, and breathing became faster when Mrs. Page screamed.

·  Impulses Continue to the Brain for Processing

• While the body reacts, the impulses also travel to the brain almost simultaneously to process the situation.

• Example: As soon as we reacted, the brain sent a message like, “Relax, it’s just crazy Mrs. Page.”