Why can human tears have different chemical compositions? Detailed answer

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Why can human tears have different chemical compositions? Detailed answer

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Why can human tears have different chemical compositions?

There are three types of human tears: basal, reflex and emotional, differing in chemical composition. Basal tears are secreted constantly in small amounts, wetting the cornea and protecting the eyes from dust and bacteria. The second type of tears is the body's reaction to irritants, such as foreign particles, onion fumes, or tear gas. The third type includes tears from emotions, both negative and positive - they stand out when a person cries. They contain specific hormones prolactin and ACTH in a much higher concentration compared to basal and reflex tears, which can be distinguished even by smell.

Authors: Jimmy Wales, Larry Sanger

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A team of researchers from the RIKEN Center for Integrative Medical Sciences has made an important discovery by finding hemoglobin in the cells of the top layer of human skin. This protein, previously known only in the blood, is now attributed to the role of a protector, capable of protecting skin cells from the effects of ultraviolet radiation.

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Researchers analyzed substances secreted by cells in different layers of the skin in humans and mice to understand how this organ protects itself from environmental influences. The study found that keratinocytes, which make up the top layer of skin, express hemoglobin genes in both humans and rodents.

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