Conversion of Fibrinogen (Cambridge (CIE) IGCSE Biology)

Conversion of Fibrinogen: Extended

Extended Tier Only

• Platelets are fragments of cells which are involved in blood clotting and forming scabs where the skin has been cut or punctured

• Blood clotting prevents continued / significant blood loss from wounds

• Scab formation seals the wound with an insoluble patch that prevents entry of microorganisms that could cause infection

• It remains in place until new skin has grown underneath it, sealing the skin again

How the blood clots

• When the skin is broken (i.e. there is a wound) platelets arrive to stop the bleeding

• A series of reactions occur within the blood plasma

• Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin and form an insoluble mesh across the wound, trapping red blood cells and therefore forming a clot

• The clot eventually dries and develops into a scab to protect the wound from bacteria entering