The Layers in Iris:
We all know Iris, let us pretend she is a girl, this is her story. Iris is always in tears, when sad, when happy or just even if something gets to her. She has special lacrimal glands to make new tears. She cries so much that she goes through ten ounces of tears per day, thirty gallons a year.
In fact if you look closely, she is crying a little all the time. That basal tears iris constantly produces form a thin coating of three layers. Right next to iris is the mucus layer which keeps the whole thing fastened to her. On top of it is the aqueous layer which keeps irias hydrated, repels invasive bacteria and protects her skin, or cornea from damage. Finally, there is the lipid layer, an oily outer film that keeps surface smooth and prevents the other layers from evaporating.
Basal Tears and Reflex Tears:
Iris usually goes through her day without noticing basal tears doing their thing. But when onions are removed from their skins, a chemical reaction happens, converting the sulfoxides into sulfenic acd, a nasty substance with a long name: syn-Propanethial S-oxide. The gas stings iris and suddenly she cannot help it, she starts weeping. These reflex tears are different from basal tears because they are designed to wash away harmful substance, they are released in much larger amounts, and their aqueous layer contains more antibodies to stop any microorganisms that maybe trying to get in, as well.
Emotional tears:
There is also emotional tears. When someone is either too happy or sad, it feels like a loss of control, which can be dangerous. So, emotionnal tears are sent in to stabilize the mood as quickly as possible, along with other physical reactions, such as an increased heartbeat and slower breathing. But scientists still are not sure exactly how or why the tears themselves are helpful. They maybe a social mechanism to elicit sympathy or show submission. But some studies have alsao found that emotional tears contain higher levels of stress hormones, such as ACTH and enkephalin, an endorphin and natural pain killer. So emotional tears are directly calming Iris down as well as signaling her emotional state to others.
Transcripted By Benazir Elahee Munni