And God Created ...

The Complexity Of Tears

David Everson

Job 16:20 "My friends scorn me: but mine eye poureth out tears unto God."

Job, in his misery at the trials and temptations from Satan and from his distress caused by his wife and so-called friends, responded as all humans do in these conditions: he shed tears. Little could Job know the complexity of such a seemingly insignificant drop of water. Only in a modern scientific lab can the true nature of a tear be discovered. Let us take just a few minutes to look at the amazing structures that produce tears and at the discoveries being made about tears even today.

Tears generally are classified into three types. They are basal tears that are considered the normal moisture for eye protection, reflex tears that are produced when a foreign substance gets onto the eye surface, and physic tears that are the emotional tears when we laugh or cry.

Tears are produced by almond-sized glands called the lacrimal glands which are located at the top of the eye. They drain out onto the surface of the eye through special excretory lacrimal ducts of which there are 6 to 12 in each eye. As tears are produced, the ducts drain them onto a special layer on the eye called the tear film. This three-layered structure sits on top of the cornea, which is the outermost layer of the eye. The tear film layers are designed to prevent evaporation of the tears while holding the lubricating tear on the eye and aiding in the prevention of bacterial infection on the eye. After the tear is moved over the eye by the eyelids, excess fluids are channeled into the lacrimal canals and from there into the nasolacrimal ducts which lead into the nose. If enough tears are present, our noses will start to "run" as the tears are drained away.

A tear has been known for years to be a watery solution which contains several salts (that is why tears taste "salty"), mucus, white blood cells, lysozyme (a bacteria fighting enzyme), and, most recently, a new class of fats, but more on that a little later. The tears we produce keep our tear film and cornea healthy as they keep these living cells of the cornea from drying out. They make a slightly acid condition that prevents bacterial growth, and then, when bacteria do make it onto the eye, they will kill the bacteria by white blood cells and enzymes. Tears are also known to aid in our ability to see as they make a perfectly smooth surface on the cornea that is necessary for light to pass through correctly so we can see without interference.

For many years, little was known about the structure of a tear. Research last year on tears revealed that a tear is made of three layers of materials. The first is a coating of oil; the second is a layer of water; and, inside, making most of the tear, is mucus. The water and mucus, which comprise most of the contents of a tear, were expected, but the discovery of oil was full of surprises. Recently, these oils in tears were found to be a previously unknown class of lipids called fatty acid amides. This class of lipids was unknown until research was done on the tear. Along with this new fatty acid material, a lipid known as oleamide, which, before its discovery in tears, was only found in the brain and central nervous system, was discovered. Both of these discoveries surprised the researchers. Further investigation showed that the lipids are responsible for "locking" the moisture of the water and mucus onto the surface of the tear film and cornea. In the brain, the oleamide is known to aid in communication between brain cells. There is speculation that there may be some communication between the cells of the eye surface, but more study will be needed to confirm this.

So, in our tears of joy and sorrow, God has buried mysteries that modern science is still trying to uncover. Let us always marvel at the wisdom of the all-knowing God, for we are truly "fearfully and wonderfully made." -Rt. 1 Box 116A, Belington, WV 26250.


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