The Secret behind the tears
A salty liquid called tears helps to clean and lubricate eyes, produced by the tear glands; those are located on the outer side of each eye, slightly above the eye and underneath the eyelid.
One of the important components of tears is lysozyme, anti-bacterial chemicals for eyes and nose (when drained into the nose through the Tear Duct, keeping the nose moist or running). The basic chemistry of tears is about water, minerals, proteins, hormones, antibodies and enzymes. The release of these chemicals as a tear has different composition which depends on type and various emotions.
There are three types of tears:
Basal Tears: Protein-rich antibacterial liquid is constantly discharged on eye-blinking by the lacrimal gland present in the outer edge of the eyeball. These tears keeps entire eye surface lubricated, nourished and protected all the time.
Reflex tears: Tears as result of irritation from chopping an onion, wind, smoke, and dust or chemicals. These tears help to flush out dirt or any object that gets into the eye and cause irritation in eyes.
Note: Volatile compound containing sulfur is released on slicing the onion which reacts with amino acid from proteins to form sulfuric acid which irritates and in response eyes tear to dilute the acid.
Emotional Tears: Emotional crying in which tears are produced in such a large quantity that they overflow, overwhelm the nasal canal of the tear duct and fall down our cheeks. This type of crying occurs in response to stress, frustration, sadness, and happiness, and any other emotion that evokes tears.
Note: Emotional tears have a different chemical composition from reflex tears and have more protein-based hormones, one of which is a natural pain killer.1 Studies have shown that emotional tears contain more manganese (an element that affects temperament) and more prolactin (a hormone that regulates milk production).2 Crying out manganese and prolactin is assumed to relieve tension by balancing the body's stress levels and eliminating build ups of the chemicals, making the crier feel better. This may be one of reason crying makes us feel better.3
1. Walter, C., Why do we cry? Scientific American Mind 2006, 17 (6), 44-51.
2. Van Haeringen, N. J., The Lacrimal System. Adult crying: A biopsychosocial approach 2001, 3, 19.
3. Fooladi, M. M., The healing effects of crying. Holistic nursing practice 2005, 19 (6), 248-255.