The Heart of the Matter

Every ten years you live, your heart pumps enough blood to fill a rocket’s fuel tank. It does this by contracting and relaxing approximately once per second, over and over and over and over again, during every moment you breath. Every cell in your body has constant need both of new oxygen and of waste removal and blood serves both purposes. Your tissues can survive a few minutes without blood but anything more than that and they start to die–your heart can’t take any time off, it has to keep pumping interminably until the minute you die.

Most people know this I suppose. The heart, though, reveals itself to be a miracle to those who study it–no matter how much I learn about it, it continues to unravel its mysteries before me, like a trail’s whose mountain majesty only increases as the trail winds on.

On a visible level, the heart is divided into atria, vetricles, and valves. The atria and ventricles are chambers, each smaller than your fist, that fill with blood and then pump the blood into your lungs and body. The atria have to contract just before the ventricles–their relative contractions can’t be simultaneous, but neither can they be separated by more than a few hundred miliseconds–deviation in either direction is disastrous.

To accomplish this unbelievably delicate balancing act, the heart employs cells of different electrophysiologic properties. The heart contracts because it is stimulated by electricity to do so–the squeeze we see when we open a person’s chest for surgery is a result of current rushing from the top toward the apex (the point at the bottom) of the heart. How, then, do we get the current to pause and allow the atria and ventricles to contract in succession? There is a fibrous ring around the heart’s center which lassoes the current and forces it into a little bundle of cells called the AV node. Once there, the current encounters a special type of cell–different from cells in any other part of the heart–which conducts current, but slowly. In other words, the current sprints from the top of the atria to the bottom of the atria, then encounters the AV node and is told, in essence, that it must slow down–jog, if you will–for a few hundred milliseconds before proceeding to the ventricles. Once it enters the ventricles, it is unleashed and begins to sprint again with abandon.

How, then, do we manage to locate such a remarkable group osfslow-conducting cells in the middle of the wall between the atria and the septum? Recall that you and I each began as a single cell. That cell contains all the genetic information necessary to build a human being. That cell contains not only the raw information, though, but also the building instructions. As the cell divides into two, then four, then eight, then sixteen, then thousands, then millions, then billions of cells, each new cell must receive instructions–one cell becomes part of your eye, one becomes part of your liver, one becomes part of a fingernail, and a few select cells become those special slow-conducting cells. Those cells not only must learn to become electricity-conducting cells, to do so they must learn to express a particualr ratio of calcium to potassium channels–this is the property that controls the speed with which they conduct.

And what about location? It is one thing to create X number of slow-conducting cells, but how do we tell those cells to group together? And how do we tell them to migrate to that little spot in the middle of the heart instead of to some equally amenable place in the spleen or the brain? Other cells secrete special chemical signals which instruct the cells concerning where they should go. This, of course, is hapenning at the same time that the liver is becoming the liver, and that the eye is becoming the eye, and that the leg is becoming the leg, and that lung in becoming the lung. And all of this, again, is proceeding forth from a single cell which somehow contained all the instruction necessary for this marvelous transformation.

All of these happen and then by some indescribable synergy the parts connect and blood begins to flow from that central organ into the aorta, the large arteries, the arterioles, and capillaries, then into veins, back to the heart, into the lungs, and back to the heart to begin the circle again.

Science has deciphered much of the code which enshrouds this mystery. We can access reams of information about the chemical and physical mediators which dictate this glorious unrolling of life. Still, at it’s fontier, science must admit to ignorance. Scientific knowledge only stretches so far, and beyond that border lie those things which, as one of my professors said, “keep scientists believing.”

In a funny way, though, it is the known–not the undiscovered–country which most strongly fuels my faith. While I do not doubt that future discoveries will testify even more strongly to the magnificence of the Creator, I am content to marvel at the intricate interweaving that already spreads itself before us. I do not mean to argue against evolution–ineed, if evolution turns out fact, the molecular mechanisms by which it proceeds are surely one of God’s most eloquent testaments to His own genius–but simply to point out the indubitable and inexplicable order which defy both our complete understanding and out total appreciation. The process by which life begins, matures, and continues certainly convinces us Someone much more intelligent than chaos is at work:

“I say unto you that if ye should serve him who has created you from the beginning, and is preserving you from day to day, by lending you breath, that you may live and move and do according to your own will, and even supporting you from one moment to another–I say, if ye should serve him with all you whole souls yet ye would be unprofitable servants.”

Published in: on October 7, 2006 at 12:31 pm  Comments (2)  

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2 CommentsLeave a comment

  1. Very inspiring to read! I remember when I was a Junior in high school taking Biology and read the text about what I think is called embryonic induction that my mind seemed so charge and thrilled as this information unfolded before me. You go into even greater detail and it has been a joy to read.

  2. Barb–

    Thank you for the kind compliments. The information is, as you point out, thrilling, not to mention baffling–how it all works is far beyond me; much more importantly, though, I think full understanding even lies beyond the comprehension of our greatest minds.

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