Tear ducts are drains at the inner edges of the eyes. Under normal conditions tears flow through the drains and down into the nasal cavity. The nasal cavity connects to the oral cavity and throat (as adventurous children discover creatively with a long piece of spaghetti), and most of those tears end up getting swallowed. At a total of around 300 milliliters (~10 oz) per day, it is not an insignificant amount of fluid. That is almost a Coke can full of tears every day.
