Why do we cry?

Lately i've been thinking about crying, why do we cry? what is the difference in tears of laughter and tears of sadness? what does crying do for us? where do the tears come from? I've meditated on this and thought about this and came back to the same answer...crying is a release of emotions.
Grieving for a loved one causes us to hold emotions in, we try to be strong for others and ourselves. We still feel the need to emotionally collapse but usually we don't give in to it as much as we should.
Crying with grief is a release of the love we have inside for the person we lost. It can be a deep racking sobbing, coupled with a feeling of helplessness and a feeling of emptiness and its a natural process. To some it can release the feelings we have of, have we done enough, what if, if only...as we cry we're letting these feeling go, for some it takes time for others it can be a quick process. But it's a natural emotion. Sometimes it you can actually feel the release, as a lighter feeling grows in your chest or as a weight leaves you. This can happen if you've realised the loved one has had enough, it's best for them or you have accepted the ineviteable. It's the ones left behind who feel the loss most.
Crying over a relationship, is like a grief, its mourning a loss, an ending. It all depends on how much love was there at the time of the end or break up, some people know when it's over but sometimes stay in that relationship a little bit longer. When that happens you might find there's very few tears if any. Some feel a sense of relief even. Sometimes when a relationship is over, you might not be crying for that person, it could be the extended relationships which have built, the bonds and the ties that you feel you lose.
Crying in pain or when we hurt ourselves is really to soothe ourselves, feeling sorry for ourselves, and you'll find as the pain of hurting ourselves goes, so does the crying. 
Emotional crying for seemingly no reason can happen when we feel out of balance, losing control, out of sync with life in general, and sometimes can have a domino effect, we look for the reasons why, we look to sometimes blame other things and sometimes it can be situations or others that can cause this crying, its the cause and effect reaction. 
So crying in general when it's to do with any kind of pain, whether a loss, an ending or actual pain is for soothing ourselves emotionally. And emotions are all from within. Hopelessness, abondonment, loneliness can all be rolled together. It's our body's own natural painkiller

Crying with joy or happiness can happen out of the blue too, if we've really looked forward to an event, meeting someone we havn't seen for sometime, can cause feelings of excitement and it can be overwhelming and we cry. We cry at jokes when we laugh. If you think, when we go through bouts of crying with sadness, there's almost always something that will pick us up and make us smile or laugh and there'll be a tear or two that come with that. We can be sad or feeling tearful and someone will say "cheer up" or try in their way to make us laugh or at least smile. This is a form of "cleansing" a carthartic or purging of the emotions.
Crying is good for us as it cleanses the emotions. If you have had a bad day, emotionally and feel stressed, a good cry at the end of the day is one of the ways the body cleanses and purges itself to pick itself and emotions up again.

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