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How does a reflex work?
Quick answer
A reflex works as an automatic, near-instant response to a stimulus that bypasses conscious thought. When you touch something hot, signals shortcut through your spinal cord to pull your hand away before your brain even registers the pain. A sensor detects a stimulus, like heat or a tap.
Step by step
- A sensor detects a stimulus, like heat or a tap.
- The signal travels to the spinal cord, not all the way to the brain first.
- The spinal cord sends an immediate command back to the muscles.
- You react before consciously feeling it — saving crucial time.
- This shortcut is called a reflex arc.
People also ask
Why are reflexes so fast?
They skip the brain's slower decision-making, routing the signal through the spinal cord straight back to the muscles.
What is a reflex arc?
The short nerve pathway of a reflex: sensor to spinal cord to muscle, which produces a response before conscious thought.
Why does the doctor tap your knee?
It triggers a stretch reflex; a normal kick shows the nerve pathway from leg to spinal cord and back is working.
Part of the guide: How Your Body Works →