Elizabeth Martin and Robert Hine. Latest Edition (7 ed.) Fully revised and updated, the sixth edition of this dictionary provides comprehensive coverage of biology, biophysics, and biochemistry, as well as key terms from medicine and palaeontology.
For example, if someone scratches a mole until it bleeds, the resulting lesion, a crust, is now a secondary skin lesion. The most common secondary skin lesions include: 1  crust: a crust, or a scab, is created when dried blood forms over a scratched and irritated skin lesion. 2  ulcer: typically caused by a bacterial infection or physical trauma. 3  scale: patches of skin cells that build up and then fall off the skin.
Clotting proteins in the blood join forces to form a fibrin net that holds the platelet plug in place over the tear, and in just a few seconds or minutes (depending on how bad the scrape is), BLEEDING STOPS, thanks to coagulation! The fibrin plug becomes a scab that will eventually fall off or be reabsorbed into the body once healing is complete. Once bleeding has been controlled, the next step is stopping infection: The blood vessels that were constricted now dilate to bring white blood cells rushing to the scene.