Ask for science, the accuracy of this speech.

Tears (yǐ nlè i) are a kind of liquid that people shed from their eyes when they are sad or too excited and happy. It tastes slightly salty. Usually, a small amount of transparent physiological saline secreted by lacrimal gland diffuses between eyeball and eyelid, making it moist and easy to move, and usually enters the nasal cavity through nasolacrimal duct. Tears are divided into two categories: reflective tears and emotional tears; Emotional tears contain more protein than reflective tears, and emotional tears contain a chemical similar to painkillers. Lactoferrin and β -lysine in tears have defensive function and can inhibit the growth of bacteria. In addition, the secretion of tears will promote the normal metabolism of cells and prevent cells from forming tumors.