Chemis-Tear-y

Tears are an intergal part of a person's life. We shed a drop of tear every now and then. Tear drops are common for lots of emotions, let it be joy or sorrow.

Tear glands are positioned on the ouside of the eyes and beneath the eye lids. It causes a thin layer of tear everytime we blink, cleaning and lubricating our eyes. One of the important components of the tears is Lysozyme also known as muramidase. Lysozyme is an enzyme that damages the cell walls of bacteria, thus inhibiting their (bacteiral) growth in our eyes. Portion of the tears that remain after evaporation drain into the nose through the tear ducts and thus keeping our nose too bacteria free.

Let us focus on what happens when we cut onions, Onions, when cut release their contents. All the contents which could not react till then now react to form some sulphur compounds, chiefly thiopropanal S - oxide. Thiopropanal S - oxide is a volatile compound and hence is easily vaporised and moves randomly, some of which land in our eyes. It reacts with water and produces Sulphuric Acid which causes the irritation in our eyes. This causes the tear glands to produce more tears as a reflex action in an attempt to dilute and wash away Sulphuric Acid that was causing irritation in our eyes.

Structure of Thiopropanal S - oxide

Scheme for conversion of Sulphur compounds in Onion to Thiopropanal S - oxide

One easy way to avoid tears while cutting onions is to refrigerate onions prior to use. Studies show that the more you cut onions onions the less you are going to be affected by Thiopropanal S - oxide.

One of the studies on tears made by Dr. William H Frey differentiates the nature of tears produces during emotional moments and the tears produced during irritation in eyes. Dr. William's team has found that emotional tears have harmones that are protien based, some of them are produced by our body when under stress. As most of them are removed when we cry, we feel good after a good long session of crying.

There is a lot of work done on tears and one goes to say that only humans shed tears in response to emotional stress.

So, Go Ahead and Cry to let all the stress out.

Cheers.

:)