Blood Clotting
When we cut ourselves we not only lose blood but we also make it easier for bacteria to get inside our bodies. Therefore the body must stop the flow of blood and block the breach in the skin to prevent blood loss and infection. For this to be effective it needs to be quick.
Platelets in the blood carry an enzyme. This enzyme is released into the plasma when the platelets come into contact with air or damaged cells.
The enzyme changes the soluble plasma protein fibrinogen into the insoluble fibrin. Fibrin is sticky and forms long threads creating a net, which traps some red blood cells. This makes a plug called a blood clot. Phagocytes, attracted to the damaged site, engulf the pathogens.
The clot hardens and becomes a scab. This protects the wound as the skin heals beneath.
