Design of Blood

Everybody knows that bleeding will eventually stop when there is a cut or when an old wound starts bleeding again. Where the bleeding is, a blood clot forms that hardens and heals the wound in due time. This may be a simple and normal phenomenon for you, but biochemists have shown through their research that this actually is the result of a very complicated system at work. The lack of any one component of this system or any damage to it would render the whole process useless.

Blood has to coagulate in the right time and place and when normal conditions are restored, the clot should vanish. The system functions flawlessly down to the minutest detail.

If there is bleeding, the clot should form immediately in order to prevent the creature from dying. Furthermore, the clot should cover the entire wound and, more importantly, should only form over, and remain right on top of, the wound. Otherwise all the blood of the creature could coagulate and cause its death, which is why the clot should form at the right time at the right place.

The smallest elements of the bone marrow, the blood platelets or thrombocytes, are crucial. These cells are the main elements behind the coagulation of blood. A protein, called the Von Willebrand factor, ensures that, in their continuous patrol of the blood stream, these platelets do not miss the place of the injury. The platelets that become entangled in the location of the injury release a substance that collects countless others to the same place. These cells eventually shore up the open wound. The platelets die after performing their duty in locating the wound. Their sacrifice is only a part of the coagulation system in the blood.

Thrombin is another protein that facilitates coagulation of blood. This substance is produced only at the location of the wound. This production must be neither more nor less than necessary, and has also to start and stop exactly at the required times. There are more than twenty body chemicals called enzymes that have roles in the production of thrombin. These enzymes can trigger its reproduction or halt it. The process is under so much scrutiny that thrombin only forms when there is a real wound to the tissues. As soon as the enzymes of coagulation reach a satisfactory level in the body, fibrinogens that are composed of proteins are formed. In a very short while, a mesh of fibres form a web, which is formed at the location of the escaping blood. In the meantime, patrolling platelets continue to become entangled and accumulate at the same location. What is called a clot is the plug that is formed due to this accumulation.

When the wound totally heals, the clot dissolves.

The system that enables formation of the clot, determining its extent, strengthening or dissolving the formed clot undoubtedly, has an absolute irreducible complexity. (1)

The system works flawlessly down to the minutest detail.