Crystallized tear. Coloured scanning electron micrograph (SEM). Tears are secreted from the lacrimal glands located at the back of the top eyelid. All tears contain water, lipids, lysozyme, lipocalin, glucose, and electrolytes (sodium, potassium, chloride, bicarbonate, magnesium, and calcium). These are what give tears their salty taste. This protein-rich, antibacterial liquid goes from the outer edge of the eyeball toward the cornea and lubricates the entire eye surface every time we blink. Magnification: x450 when printed at 10 centimetres wide.