2006-10-21 20:25:45 · 9 answers · asked by isabelle 2 in Education & Reference ➔ Homework Help
To clean the eyes. Birds have a clear eyelid to do this for them.
2006-10-21 22:29:11 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Why do we blink?
We blink as frequently as every four to six seconds. In fact, blinking happens so quickly that it doesn’t obstruct our vision. But what purpose does blinking serve?
The eyelids are folds of skin controlled by muscles that can expand and contract very rapidly. Between our eyelashes, just inside the rims of the eyelids are 20-30 sebaceous glands as well as tear glands. When we blink, these glands secrete lubricants that prevent the eyes from drying out. Each time the eyelids close, salty secretions from the tear glands sweep over the surface of the eye, flushing away small dust particles and lubricating the eyeball. Our eyelashes serve as dust catchers, because the reflex action of blinking automatically causes them to lower when exposed to some kind of foreign particles.
If you are in irritating conditions such as a smoke-filled room, you blink more frequently to keep the eyes clean and moist. You should also blink more often, even consciously, if you wear contact lens or sit before the computer screen for long periods of time.
2006-10-22 03:37:14 · answer #2 · answered by Jeremysmom05 3 · 0⤊ 0⤋
Eyes open and close so that the eye is adequately lubricated and cleaned. Dust and foreign bodies can enter the eye and the lubricated eyelids act like wipers, cleansing the eye and keeping its moisture level adequate.
2006-10-22 06:11:57 · answer #3 · answered by MAC C 3 · 0⤊ 0⤋
they are spreading your tears over your eyeballs. The cells on the surface of your eyes need to be constantly moisturized. Think of your eyelids as your windshield wipers.
2006-10-22 03:29:57 · answer #4 · answered by DANIEL R T 2 · 1⤊ 0⤋
eyes do not open and close
it's the eye lid that open and close
i had a hard time figuring out that too lol!!
2006-10-22 03:27:36 · answer #5 · answered by phoebe l 1 · 0⤊ 0⤋
Because it is harder to sleep with your eyes open...
2006-10-22 03:34:02 · answer #6 · answered by Timothy C 5 · 0⤊ 0⤋
hey good answers i never really thought about it but im just happy they do because if someone were to tape them open and you couldn't blink that would be torture
2006-10-22 03:44:37 · answer #7 · answered by Up_In_Smoke 2 · 0⤊ 0⤋
Because they can.
2006-10-22 03:44:35 · answer #8 · answered by Dr Know It All 5 · 0⤊ 0⤋
to click everything you see
2006-10-22 03:35:42 · answer #9 · answered by guharamdas 5 · 0⤊ 1⤋