HumansHuman Body

What is a reflex?

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A reflex is a reaction our bodies have without us even having to think about it! It's an automatic response that we can't control. Most of the time, reflexes are a way for us to move or protect ourselves in a hurry.

If someone taps you on the nose, your eyes will blink (unless you know it's coming and you try really hard to fight it!). This protects our eyes in case the object tapping your nose is something that could hurt them. The blinking is also called "flinching," and it is just one of many reflexes that our bodies experience.

If the doctor taps your with that special triangular hammer and you kick your leg, that's a reflex too. Some people even have a reflex that makes them sneeze if they see bright light!

(by Mya Kagan)

Exploration

The Eyes Have It!

Here's one reflex you can check out for yourself pretty easily. It's called the pupillary light reflex, and that just means that the pupils (or black dots) of your eyes change size depending on how much light is around you.

Stand in front of a mirror in a darkened room. Make sure it's not too dark that you'll bump into things and hurt yourself. Wait a few moments for your eyes to adjust, and then turn on the lights! What happens to the pupils of your eyes? They get smaller!

It's the pupil's job to let light into our eyeball for us to see. Why do you think it changes size when a room gets darker or lighter?