Blood Clotting (DP IB Biology)

The Process of Blood Clotting

Platelets

• When the skin is cut, microorganisms have an entry point to get into the body

  • The first line of defence is compromised

• In order to minimise the risk of substantial blood loss and entry of unwanted microorganisms, the blood starts to clot and seal the wound

• In response to blood vessel damage, platelets form a temporary plug to stem bleeding

  • Platelets are cellular fragments that make up one component of the blood

• They release chemicals called clotting factors that trigger a chemical cascade which results in blood clotting

Components of Blood Diagram

The blood is made up of 4 key components; plasma, red blood cells, white blood cells and platelets

Blood clotting process

• The chemical cascade, triggered by the clotting factors, involves a large number of steps and several plasma proteins

  • First of all, the clotting factors stimulate the release of the enzyme thrombin

  • Thrombin catalyses the conversion of the soluble protein fibrinogen into fibrin, which is insoluble

  • Fibrin forms a mesh that traps more platelets and blood cells to prevent entry through the wound

    • A small initial stimulus is amplified to produce a large amount of fibrin so that the wound is quickly sealed

  • Exposure to air results in the hardening of the mesh to create a scab

Blood Clot Formation Diagram

Blood clotting involves a chemical cascade process