Understanding Tears  woman crying  We produce tears for many
reasons. Our eyes may be brimming with tears when we cut up an
onion, suffer from seasonal allergies, or when foreign objects
irritate our eyes. We may also shed tears when we get too
emotional or when we feel extreme pain. In many cases, yawning
and urinating can also make us cry.  3 types of tears  Tears are
categorized as basal, reflex, and emotional. All of these types
occur for different reasons. We release basal tears regularly to
keep our eyes lubricated. Basal tears contain water, mucin,
lysozyme, lipids, lipocalin, lactoferrin, immunoglobulins,
lacritin, urea, glucose, potassium, and sodium.  There are also
the reflex tears, which we produce when our eyes get irritated.
These tears have the same chemical make up as basal tears.
Lastly, we produce emotional tears when we feel strong emotions
such as anger, sadness, and even laughter. We also tend to
produce tears due to physical pain.  Many researchers suggest
that our body can’t differentia