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The human tear ducts are small tubes stretching from the eye to the nose. They drain tears. It is officially known as the nasolacrimal duct that controls the flow of excess tears. The tear gland responsible for producing tears is located in the upper eyelid. The tear ducts that release the tears are located in the inner corner of the eye closest to the nose. Tears are an important method of keeping eyes clean and healthy. They also contain enzymes that destroy certain types of bacteria that may cause damage to the eye.
How It Works
The tear duct works by releasing tears into the eye when stimulated. When a person cries or feels a sharp pain, the tears are released instinctively. In actuality, tears are the body's natural way of lubricating the eyes and keeping them clean of foreign substances. Tears also rid them of dirt and bacteria. The tear ducts release the liquid into the eyeballs between the eyelids. The tears flow down when the eyes blink, causing the liquid to spread across and outside the eye. Excess tears can flow into the nasal cavity through the nasolacrimal duct, causing the nose to run.
Types of Tears
There are basically three types of tears: reflex tears, basal tears and crying tears. Reflex tears are stimulated when something foreign like an eyelash or speck of dust falls into the eye, causing pain and discomfort. The tear glands naturally produce tears in order to wash out the foreign substance in the eye. Basal tears are naturally lubricating tears that occur in humans and other mammals. These types of tears are meant to moisturise and clean the eyes. Finally, crying tears occur only in humans as a result of severe pain or emotional distress.