Facts about Tears

1. 08

   Meibomian glands located along eyelid margins secrete lipid-rich meibum that comprises approximately 25% of tear film composition and prevents rapid tear evaporation.

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2. 07

   In 1981, ophthalmologist William Frey discovered that emotional tears contain 24% higher concentration of manganese than basal tears, which may explain mood improvement after crying.

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3. 06

   Crocodiles produce tears to regulate salt levels in their bodies, leading to the expression 'crocodile tears' for insincere crying.

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4. 05

   Tears contain lipids that form a protective oil layer on the eye's surface, which is why deficiency in this lipid layer causes dry eye syndrome affecting millions worldwide.

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5. 04

   Humans cry reflex tears within 0.5 seconds of eye irritation, but emotional tears take 30 seconds to 5 minutes to form and release.

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6. 03

   Onions release syn-propanethial-S-oxide gas when cut, which irritates tear glands and causes crying without any emotional response from the person handling them.

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7. 02

   Emotional tears contain higher levels of the hormone prolactin and the protein lysozyme than basal tears, which explains why crying releases stress hormones from the body.

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8. 01

   The lacrimal gland produces approximately 0.5 to 1.2 milliliters of tears daily to maintain eye lubrication and health.

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