Why do tears taste salty?

Body fluids like sweat and tears are salty to taste and this has physiological, immunological and evolutionary significance. Tears are the secretions of lacrymal glands of eyes. These tears are classified into basal, reflex and psychic tears. The salinity and chemical composition of tears vary from type to type and situation to situation. Basal tears are responsible for keeping the cornea of eye moist. Reflex tears are produced during eye irritation. Psychic tears are produced during weeping. Tears contain greater quantities of water along with other organic and inorganic chemical components like mucin, lipids,lysozyme, lactoferrin, lipocalin,lacritin, sodium and potassium. The salinity of tears is attributed to the presence of salts of sodium and potassium. This salinity of tears along with the presence of enzymes like lysozyme is responsible for their antimicrobial activity. Basal tears have a salt content similar to blood plasma. The salinity of basal tears disturbs the osmotic balance of bacteria and keeps the cornea in a healthy microbial-free environment. The mineral content of tears also nourishes the tissues associated with eyes. Saline nature of tears also indicates our evolutionary descent from marine organisms. G.L.N.PRASAD , Head, Department of Zoology, Govt. UG & PG College, Anantapur, Andhra Pradesh