On Blood

On Blood

Saturday, October 2, 2010

One of my fascinations has always been the human body, specifically how the body is structured and how it works. I remember the first time I got to actually observe the human body up close. I was taking a college math class at our local community college while a junior in High School. I heard that the Biology teacher from my school was taking a few students to the college to look at a cadaver, and through some turn of fortune I got to tag along (I think looking back it was because I snuck in!) I found the cadaver fascinating, and in another life I can imagine I may have been a medical doctor, surgeon, or coroner, which probably explains why I like the CSI and Bones television shows so much.

This fascination caused me to begin reading an old anatomy book before going off to sleep. I found it so fascinating that I read the whole thing, almost a thousand pages. While reading the book I was struck with the wonder and design of the human body, how each and every part works together to sustain life, and how impossible it was for me to believe it just evolved from some random chemicals in a pool of water billions of years ago. To be honest, I believe it takes a lot more faith to believe in evolution than it does to believe in an infinite God who created the universe and all that exists in it. Every time I turned the page in this book, I was faced with the unshakeable thought that there has to be designer that created life, and any other explanation bordered on insanity.

One of the chapters that most fascinated me was the one on blood, the “River of Life.” The evolutionist tell us that the basic constituents of blood compare favorably with sea water, and hence that somehow this fluid that sustains life found its beginnings in ancient oceans and through the course of billions of years reached its current state of complexity. That explanation, quite honestly, is incredulous, and can only be believed by someone who has a priori ruled out God and a creator. Here are some of the fascinating things I found out about blood. Note that for purposes of brevity, I will only be looking at red blood cells, not the many other cells and fluids that make up whole blood.

The human body contains about 100 trillion cells, of which 25 trillion, or 25% are red blood cells. Red blood cells are produced in the bone marrow, and have a life span of about 120 days. After that they break down and are dissolved in the blood plasma or destroyed by phagocytic (white blood) cells. The broken down red blood cells are then filtered out of the blood by the spleen and kidneys. In those 120 days, the average red blood cell travels about 700 miles through the circulatory system being subjected to the pressures of being pumped through the heart and squeezed through capillaries little larger than the diameter of the red blood cell itself.

If one examines a red blood cell, or erythrocyte, one is struck with its design. Each cell contains about 280 million molecules of hemoglobin, each consisting of four globular subunits each containing a single heme molecule. Since each heme molecule can transport a single molecule of oxygen that means each red blood cell can transport about 1 billion molecules of oxygen! 

The shape of the red blood cell is that of a disk with the center depressed in on each side. This increases the surface area of the cell such that in each human adult there is about 3800 square meters of red blood cell “surface area” exposed to enable gas transport. Additionally, the shape of the red blood cell allows them to form “stacks” as they pass through capillaries thus preventing blood clots. In fact, if the red blood cell was any other shape that the one it is, it would tend to form clots and blockages – clearly an indication that its very shape was designed perfectly to sustain life as we know it.

When we examine the hemoglobin molecule more closely, we are amazed at its shape and chemical composition. The heme molecule is perfectly designed, both chemically and structurally, to transport a single oxygen molecule. Its very shape, the way the atoms are connected to one another, enables it to do this! Again, this is evidence of design! Any other shape, or any other chemical combination, will not work and life as we know it would be impossible except on a cellular level.

The process that enables blood to transport oxygen to the cells of the body and transport carbon dioxide away is fascinating in its own right. When the concentration of oxygen in the environment of the red blood cell is high, it absorbs that oxygen into the heme molecule. When the oxygen levels fall, as in the capillaries, the heme molecule then readily gives up the oxygen molecule. At the same time the globulin part of hemoglobin absorbs carbon dioxide in the cellular tissues where its concentration is high, and releases it in the lungs where the carbon dioxide pressure is low. This means that both globulin, and heme work together to transport oxygen to the cells of the body and remove carbon dioxide. Both must be together, and both must work together, or life cannot exist. Furthermore, both were designed to specifically work with the gas pressures that exist in our atmosphere and bodily tissues. At other pressures and concentrations, this process breaks down and life cannot exist. Too much carbon dioxide in the air does not allow the hemoglobin molecule to absorb oxygen, and cells of the body begin to die.

Another area where one can see design is in the way blood clots to prevent one from bleeding to death. Medical science has identified 13 separate clotting factors that need to exist in whole blood for the clotting process to work, and they must exist in the exact proportions we find them in or clotting does not occur. These clotting factors consist of calcium ions, fibrinogen, various enzymes, and other proteins. Any living entity missing one or more of these clotting factors suffers from excessive bleeding, and if the wound is serious enough it will die as the blood cannot clot to stop the bleeding. Even small wounds in such cases can prove fatal.

Another wonder of the clotting process is that it cannot work inside the body, as if it did blood clots would form in the various blood vessels of the body and one would quickly die. Clotting only occurs when a vessel wall is breached, and only then in the presence of air. The wonder of this process clearly speaks to a designer. To think that natural processes over millions of years stumbled upon the exact proteins, enzymes, ions, and fibrin structures to allow higher forms of animals to survive is ludicrous.

The process of eythropoiesis, or blood cell formation, is another wonder of the human body. Various regulatory factors, including the hormone erythropoieten, cause the bone marrow to increase red blood cell production. Normally, about 3 million new red blood cells enter circulation every second, but when the conditions demand it, the bone marrow can increase production ten-fold to about 30 millions per second. That is why people who live in higher altitudes have more red blood cells as they are needed in order to absorb lesser concentrations of oxygen at those levels.

The bottom line in all this is the clear conclusion that blood was designed specifically to perform the way it does, and were it to perform in any other way complex life forms could not exists. The physical shape of the hemoglobin molecule allows it to perfectly function by carrying oxygen from an environment where the oxygen pressure is high to an environment where it is low, while at the same time picking up carbon dioxide in an environment where its concentration is high and carrying it to an environment where it is low. Additionally, the very shape of the red blood cell allows it to circulate through the blood vessels and capillaries of the human body without clogging – any other shape would not work. And finally, the existence of 13 specific clotting factors that work in perfect unison to clot blood in the case of a wound points to design. If any one of them is missing, the organism bleeds to death.

And so I can reach no other conclusion, but that blood was created by God to perfectly work exactly the way it does, and as a result He gets all the credit for its wondrous design. We are truly fearfully and wonderfully made.