The protein thrombin allows the blood to clot by converting fibrinogen to fibrin. Even though this protein is always circulating through the blood, however, it doesn't always lead to the clotting of blood, thereby preventing blood flow. If there is bleeding in one blood vessel only, it "understands" that clotting is needed there and sets about clotting the blood. If thrombin always led to clotting, all of the blood in the vessels would clot as a result of the thrombin present, and the body could not survive with its circulation totally blocked. So how does thrombin attain the ability to cause clotting only in the place where it's needed?
Thrombin is usually present in blood plasma in an inactive form called prothrombin. Being inactive, it cannot perform the duty of clotting and in this way we are protected from the fatal consequences of uncontrolled clotting.
But what activates prothrombin and converts it to the clotting factor thrombin when bleeding occurs?
A protein in the blood called Stuart factor has the effect of converting prothrombin to thrombin. However Stuart factor is itself also present in an inactive form, and needs to be activated.
At this point we are faced with a chicken-and-egg scenario. Still another protein called accelerin is needed before Stuart factor can become active and turn prothrombin into thrombin—thereby stopping any bleeding in the organism. But what's truly remarkable is that accelerin, too, is present in an inactive form of its own, called proaccelerin. And what activates proaccelerin?
Thrombin!
But if you recall, thrombin comes after proaccelerin in this chain reaction. This sequence of events, in which thrombin plays a role in the production of accelerin, is like a grandchild being born before its own grandmother. But because the effect of Stuart factor on prothrombin is very slow, small amount of thrombin is always present in the blood. As a result, this small amount of thrombin first activates accelerin and then, each of the proteins needed for clotting go into action, like cascading dominoes.
We've explained here only the very superficial facts about the clotting process. To claim that this whole system—consisting of so many parts working together interdependently, with each part performing its duty without neglect—is all the result of coincidences is illogical and irrational.
At the site of a wound, many interdependent proteins go into action to allow blood clotting. These proteins, activated when the body receives a wound, in turn activate each of the other proteins required for clotting. |
Evolutionists do claim that living things, together with all their systems including blood clotting, evolved step by step. But in order for clotting to take place, all the proteins and enzymes involved depend on one another. Remove one component, and all the rest are rendered useless—and would actually lead to the death of the organism. As a result, any organism with an incomplete clotting system wouldn't have time for the other parts of the system to be completed and would die long before it could reproduce. Consequently, this one example invalidates the claim that organisms evolved from intermediary species. But we could multiply these examples exhaustively, because living bodies continue their existence on behalf of hundreds of such interdependent systems.
The Creator of all of these systems is God.
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