While some other animals are known to cry in response to pain, as well as shed tears to lubricate their eyes, scientists believe that humans are the only species known to shed tears as a response to different emotional states.
Human tears are an antibacterial liquid that is secreted from the lacrimal glands (located at the upper, outer part of each eye socket. Tears serve mainly to lubricate the eyes, protect them from infections and help you see things clearer. Excess tears are usually drained into a passage that leads from the inner part of your lower eye lids into the back of your nose.
There are three types of tears:
- basal tears- tears shed to lubricate the eyes.
- reflex tears- usually shed to wash away irritants like dust or a foreign body in the eyes
- emotional tears- tears shed as a result of sadness, sorrow, happiness or other emotional states
We shed tears when we secrete more tears from our lacrimal glands than can be drained.