Scientists distinguish three kinds of tears, which differ from each other by function and also, probably, by composition. Basal tears actually form continuously. We don't experience these minute secretions as tears because they don't "ball up" as we are used to tears doing; instead, every time we blink, our eyelids spread the basal solution out over the surface of our eyeballs. Basal tears keep our eyes lubricated, important in preventing damage by air currents and bits of floating debris.
Basal tears, like all tears, have numerous components. A little bit of mucus allows them to adhere to the eye surface without causing harm. The main part of a tear contains, predictably, water and salts (like sodium chloride and potassium chloride). The ratio of salt to water in tears is typically similar to that of the rest of the body, so there is no net change in salt concentration; nonetheless, if the body's salt concentration climbs too high, it will take advantage of the tear solution and instill it with extra salt. Tears also have antibodies that defend against pathogenic microbes, and enzymes which also contribute to destroying any bacteria the eye encounters. A thin layer of oil covers the tear's outside to discourage it from falling out of the eye before its work has been done.
Our eyes produce irritant tears when hit by wind or sand (or insects or rocks). Irritant, or reflex, tears have the same constituents as basal tears, and work toward the same goal: protecting the eyes. However, since they are designed to break down and eliminate eyeball-intruders like airborne dust, these tears tend to flow in greater amounts and probably contain a greater concentration of antibodies and enzymes that target micro-organisms. Thus, irritant tears are not just basal tears in greater quantity; different biological processes precede the excretion of the two types of solution.
The voluminous tears that so rapidly move us to frustration or pity are, of course, emotional tears. Secreted in moments of intense feeling – sometimes joy, but more often sorrow – these tears aren't there to cleanse the eyes of irritating microbes or debris. Yet they do serve a purpose; the function of emotional tears can be inferred from their constituents. Emotional tears contain much more (maybe 25% more) than basal or irritant tears of a certain important ingredient: proteins.
What do proteins do? Well, what can't they do? We know very well they can be involved in anything and everything. The proteins found in emotional tears are hormones that build up to very high levels when the body withstands emotional stress.
If the chemicals associated with stress did not discharge at all, they would build up to toxic levels that could weaken the body's immune system and other biological processes. But here, as in other areas, the body has its own mechanisms of coping. We secrete stress chemicals when we sweat and when we cry. Clearly, then, it is physically very healthy to cry, regardless of whether or not it feels awkward or embarrassing socially. The reason people will frequently report feeling better after a well-placed cry is doubtless connected to the discharge of stress-related proteins; some of the proteins excreted in tears are even associated with the experience of physical pain, rendering weeping a physiologically pain-reducing process. Conversely, the state of clinical depression – in which many of the body's self-healing processes appear to "shut down," including, often, emotional tears – is most likely exacerbated by the tearless victim's inability to adequately discharge her pent-up stress. Psychologists refer to freely weeping as an important stage in the healing process. But although this notion may appear to be psychological in origin, involving the confrontation of one's own grief, it also just applies physiologically: crying can reduce levels of stress hormones.
Originally posted by ElOmen
This should get interesting. Why dont you start off by telling us what are the reasons you cry?
Im also interested to know why the body reacts the way it does as the OP explained when you cry.edit on 17-2-2013 by ElOmen because: (no reason given)
Originally posted by RooskiZombi
Aren't human beings the only ones that have this ability?
Originally posted by DAZ21
Crying is a natural process by the body to expel grit and dust from the eyes.
I think that our emotions simply utilize certain parts of the brain that control the tear ducts. So although it might seem like there would be a reason, It's simply just a coincidence.
Originally posted by slowisfast
Why do you laugh?
Why do humans make little yelping noises, as unique as we are, when we find something funny?
On that note, what is funny? What makes something funny?
Why is it that something can be funny to one person yet off-putting to another?
Why is it that what makes you cry makes me laugh and vice versa?
So many questions with so few answers.
I'm just grateful that to be here to experience the wide array of emotions a human can.
Did you know that the average male ejaculate has 180-400 million sperm!?
WE SHOULDN'T EVEN BE HERE!
Yet we are. We beat the odds and won the race and get to experience this thing called life.
We get to cry and laugh and run and fart and love and and and.
We get to live.
(this is where you can insert the Inception gong)