water, and they have a similar structure to saliva. Besides water, they contain salt, oils, and about 1500 proteins. They also have electrolytes: sodium, bicarbonate, chloride, and potassium.
They contain lower levels of magnesium and calcium. When you add all these chemicals together, you get three layers that make up the tears.The mucous layer is the one that sticks the tear to the eye.
The aqueous layer is the one that hydrates, repels bacteria, and protects the cornea. And the oily layer prevents the other two layers from evaporating.
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