The primary acid present in human tears is sialic acid.
Sialic acid is a generic term for a family of nine-carbon monosaccharides that are derivatives of neuraminic acid. It's a component of glycoproteins and glycolipids found on the surface of cells and in bodily fluids, including tear fluid. While tears are primarily composed of water, electrolytes (like sodium, potassium, and chloride), proteins (like lysozyme), and lipids, sialic acid contributes to the complex biochemical composition of the tear film.
Role of Sialic Acid in Tears:
While not the most abundant component, sialic acid plays a role in:
- Maintaining Tear Film Stability: Sialic acid's negative charge contributes to the overall charge of the tear film, which helps to keep the tear film evenly distributed across the surface of the eye, preventing dryness.
- Hydration: It contributes to the hydrophilic properties of the tear film.
Therefore, when considering the acidic components of human tears, sialic acid is a key one to identify.
