Page 149 - The Cell in 40 Topics

hen you cut yourself, or when an old wound starts bleeding
again, you know that the bleeding will eventually stop.
Over the area concerned, a scab will form that will gradu-
ally harden, and under it, the wound will heal itself.
This may seem to you to be quite a simple matter. The fact is, how-
ever, that biochemists’ research has revealed that this is the result of a
26
highly complex system. The absence or impairment of any of the compo-
nents of this system will mean it fails to function at all.
The blood must clot in the right location and at the right time, and it
must cease when local conditions return to normal. The system must func-
tion flawlessly, right down to the very smallest detail.
In the event of bleeding, clotting must take place at once if the organ-
ism concerned is not to die from loss of blood.
Furthermore, clotting must take place along the extent of the injury
and, most importantly, must be limited to only the site of that injury.
Otherwise, more blood clotting will result in the death of the organism. For
that reason, blood clotting must be kept under tight supervision; the scab
must form in the right place at the right time.

147