Why do we blink?

[somebody]

This may seem very simple to some of you but for me, i am talking lots of bio courses and they get so into detail that they divert attention from small things like my questions here.

 

So why do we blink? And going one step further, different mammals and invertebrates can keep their eye open for different amount of time until they blink? Also, when you keep your eye open for a while you feel little burning/cooling (for me atleast) sensation and your eyes kind of get watery, WHY?

 

Thanks

[Queso]

Probably from all the dusty particles in our ozone. Blinking is like windshield wipers.

[LJP07]

Blinking is like windshield wipers.

 

I suppose I can use that analogy.

 

Think of a reasonably warm day and your sitting in your car. The front mirror is dry so you squirt the water onto it and at the same time you activate the windshield wipers, it keeps the cornea and conjunctiva moist so it doesn't dry up.

 

Also, there is NaCl in tears and this chemical can be used to lyse bacteria and also helps remove any foreign debris that might dry and enter the eye. The eyelashes also work with this mechanism to achieve this.

 

Children, or babies do not produce tears in the first month or so of life. This is counteracted by the fact that they sleep an awful lot and their eyelids are shut more.

[Pyrotex]

Because we can't handle reality.

 

:)

[LJP07]

And going one step further, different mammals and invertebrates can keep their eye open for different amount of time until they blink? Also, when you keep your eye open for a while you feel little burning/cooling (for me atleast) sensation and your eyes kind of get watery, WHY?

Nice one Pyrotex :)

 

To be honest, I'd expect a person majoring in Biology to figure this out for themselves as I did and I'm only in first Pharmacy.

 

In relation to other mammals, they also blink which means that it must serve around the same function as humans, some may blink more due to parasites or fleas etc, while some may have larger amounts of tears to blanket the cornea which means it takes less time for the next consecutive blink.

 

The reason why your eyes get watery is because there is a build up of tears around the duct that would otherwise be used in blinking regularly that the brain tells them it needs to blink, so they fall down and fill the eye up due to them not being used regularly as there is a constant production usually. The cooling I imagine is because the air is getting at the eye while irritating the outer edges ( maybe the burning sensation ) because you are straining the muscles ( The eye is co-ordinated by many muscles and nerves ).

[Boerseun]

I think more than dust, blinking is primarily about lubriction. Your cornea has to change shape all the time as you focus, and if your eyeball goes all dry, focusing will suffer.

 

Sooooo... lube, would be my guess.

[somebody]

haha, i didnt figure it out as a bio student becuase, courses that my adviser suggests are mostly genetics, molecular and courses relavent to that, i haven't had any anatomy (YET) so i dont have enough knowledge to figure this out.

 

But answer makes sense..

 

thank you

[LJP07]

You misunderstood my point: Because you are a biology student, I figured this stuff out in late high school/secondary school with basic biology, so should you if you are a scientist at all.

[Hyba]

Not really as simple a question as some suggest. If it is that easy pleae explain how lions (as an example) can tolerate flies/dust/plants in their eyes as they go in for kills, which require absolute co-ordination.

 

Eyelashes play a part, but there is a tolerance to eye contact that the brain is absolutley instructed to force you to blink. In certain circumstances the brain can turn this impulse off.