God popped me with two quick lessons as I drove to the hospital in
Lesson One: Don't take the miracle of seeing for granted!
Lesson Two: Some blind people have amazing sight! (See next post below!)I had been going over all the “stuff” I needed to get down and wondering how I was going to get it done, and not once the whole day (or week for that matter), had a paused to thank God for the amazing job He did in designing my sight. Did you know….(Warning, you may want to skim the following small print…it’s long to make a point…that seeing is a wonder we seldom reflect upon. Remember, what you are about to skim is happening trillions a time a second, and doesn’t even touch what the brain is doing with the information the eye is constantly sending it!) Anyway, as I said, “did you know that…
when photons hit the cells of the retina, they activate a chain reaction, rather like a domino effect. The first of these domino pieces is a molecule called "11-cis-retinal" that is sensitive to photons. When struck by a photon, this molecule changes shape, which in turn changes the shape of a protein called "rhodopsin" to which it is tightly bound. Rhodopsin then takes a form that enables it to stick to another resident protein in the cell called "transducin".
Prior to reacting with rhodopsin, tranducin is bound to another molecule called GDP. When it connects with rhodopsin, transducin releases the GDP molecule and is linked to a new molecule called GTP. That is why the complex consisting of the two proteins (rhodopsin and transducin) and a smaller chemical molecule (GTP) is called "GTP-transducinrhodopsin".
The new GTP-transducinrhodopsin complex can now very quickly bind to another protein resident in the cell called "phosphodiesterase". This enables the phosphodiesterase protein to cut yet another molecule resident in the cell, called cGMP. Since this process takes place in the millions of proteins in the cell, the cGMP concentration is suddenly reduced.
How does all this help with sight? The last element of this chain reaction supplies the answer. The fall in the cGMP amount affects the ion channels in the cell. The so-called ion channel is a structure composed of proteins that regulate the number of sodium ions within the cell. Under normal conditions, the ion channel allows sodium ions to flow into the cell, while another molecule disposes of the excess ions to maintain a balance. When the number of cGMP molecules falls, so does the number of sodium ions. This leads to an imbalance of charge across the membrane, which stimulates the nerve cells connected to these cells, forming what we refer to as an "electrical impulse". Nerves carry the impulses to the brain and "seeing" happens there.
In brief, a single photon hits a single cell and, through a series of chain reactions, the cell produces an electrical impulse. This stimulus is modulated by the energy of the photon, that is, the brightness of light. Another fascinating fact is that all of the processes described so far happen in no more than one thousandth of a second. Other specialized proteins within the cells convert elements such as 11-cis-retinal, rhodopsin and transducin back to their original states. The eye is under a constant shower of photons, and the chain reactions within the eye's sensitive cells enable it to perceive each one of these photons.
WOW! Here's a picture of the chemistry of sight going on right now in your eyeballs in case you skipped the small print!
Didn’t know you were carrying around such amazing biochemical processing plants in you’re your head did you!!!! Add to these reactions that ability with a second for the brain to process these trillions upon trillions of bits of information, and then, almost instantaneously compare them to memory cells, so you can recognize a person, determine their current emotional state by their expression and then respond appropriately. It’s a wonder our heads don’t explode with all that’s going on in there!
During the Christmas season as you “see” the sights, the lights, the faces of family and friends, take a moment to remember Proverbs 20: 12 Ears that hear and eyes that see— the LORD has made them both. Thank Him for this amazing gift!
Oh, and one more thing about the wonder of seeing! Do you remember the first thing the shepherds said once the angels had delivered the news that a Savior had been born in