Why humans cry?

Question

Why humans cry when they are sad or happy?

Answer 1

Types of tears
There are three very basic types of tears:

Basal tears: In healthy mammalian eyes, the cornea is continually kept wet and nourished by basal tears. They lubricate the eye and help to keep it clear of dust. Tear fluid contains water, mucin, lipids, lysozyme, lactoferrin, lipocalin, lacritin, immunoglobulins, glucose, urea, sodium, and potassium. Some of the substances in lacrimal fluid fight against bacterial infection as a part of the immune system.

Reflex tears: The second type of tears results from irritation to the eye by foreign particles, or substances such as onion vapors or tear gas or pepper spray. These reflex tears attempt to wash out irritants that may have come into contact with the eye.

**Crying or weeping: The third category, generally referred to as crying or weeping, is increased lacrimation due to strong emotional stress, depression or physical pain. This practice is not restricted to negative emotions; many people have been known to cry when extremely happy. In humans, emotional tears can be accompanied by reddening of the face and sobbing — cough-like, convulsive breathing, sometimes involving spasms of the whole upper body. Tears brought about by emotions have a different chemical make up than those for lubrication.[2]

Answer 2

I don't know the medical reason . someone else may have knoledge about this.
There have been humans that never cry ; perhaps like a crocodile

Answer 3

Dont you ever cry? Why if yes? Thats the answer !!!!

Answer 4

It is kinda weird when you think about it, I guess. But it's just how we release emotions.

Answer 5

It is just a natural reaction to things.

Answer 6

cause its a flood of emotion from the heart

Answer 7

the better question would be why do Vulcans not cry?

Answer 8

emotional release

Answer 9

i think it's a way to relieve stress

Answer 10

tear ducts