4.1 Enzyme Cascade

Blood clotting- Enzyme Cascade

1. Damage to capillary wall, exposes collagen fibres (help keep capillary wall strong) in wall of capillary= blood

Platelets, (act as a temporary plug), in blood stick to exposed collagen fibres, form a plug to stop bleeding. Platelets become activated and release clotting factors called thromboplastins.

Through a complex cascade, thromboplastins convert prothrombin (an inactive plasma protein) into thrombin (an active plasma protein) . Process requires calcium ions and vitamin K.

Thrombin catalyzes conversion of soluble fibrinogen (globular) into insoluble fibrin.

Fibrin (fibrous protein) forms a fibrous mesh that traps RBCs and strengthens the platelet plug, forming a clot

Blood clot eventually reabsorbed by another complex after new skin is completed