Advertisement Upgrade to remove ads


the clear tissue that covers the front of the eye and protects the eye


an opening in the eye which lets the light enter the eye


a circular structure that surrounds the pupil and regulates the amount of light entering the eye (comes in different colors)


a flexible structure that focuses the light


a layer of receptor cells that line the back of the eye


can see nearby objects clearly


can see object far away clearly


membrane that vibrates when sound strikes it


snail-shaped tube that is lined with receptor cells that respond to sound

semicircular canal

structures in your ear that are responsible for your sense of balance

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording