Blood coagulation

1
Blood coagulation
2
Blood coagulation

• Over 40 different substances that affect blood
  coagulation
• Procoagulants vs. anticoagulants
• Normally anticoagulants predominate in the blood
• When vessels rupture procoagulants in the area
  become dominant

3
General Mechanism

• A substance or complex of substances called
  prothrombin activator is formed in response to
  rupture of the vessel or damage to the blood
  itself.
• The prothrombin activator catalyzes the
  conversion of prothrombin into thrombin.
• The thrombin acts as an enzyme to convert
  fibrinogen into fibrin threads that enmesh
  platelets, blood cells and plasma to form the
  clot itself.

4
Conversion of Prothrombin to Thrombin

• Prothrombin activators form as a result of a
  rupture in the blood vessel or as a result of
  damage to special activator substances in the
  blood

5
Prothrombin to Thrombin

• Prothrombin activators cut the large prothrombin
  into the smaller active thrombin.
• Prothrombin is formed continually by the liver
  and is contiunally being used throughout the
  body.
• Lack of vitamin K or the presence of liver
  disease prevents normal prothrombin formation

6
Fibrinogen to Fibrin

• Fibrinogen is a large heavy serum protein that is
  produced by the liver.
• Because of its large size, rarely does fibrinogen
  leak into the interstitial fluids.
• Trauma to the blood vessel walls allows
  Fibrinogen to leak into the tissues

7
Fibrinogen to Fibrin

• Thrombin cleaves 4 low weight peptides off
  fibrinogen, forming a Fibrin monomer.
• Within seconds, fibrin monomers spontaniously
  polymerize with other fibrin monomers forming
  long fibrin threads. These threads form the
  reticulum of the clot.