body fluid secretion secretion by tissue tear secretion The regulated release of the aqueous layer of the tear film from the lacrimal glands. Tears are the liquid product of a process of lacrimation to clean and lubricate the eyes. Tear fluid contains water, mucin, lipids, lysozyme, lactoferrin, lipocalin, lacritin, immunoglobulins, glucose, urea, sodium, and potassium. GO:0070075 biological_process