1. Stage 1: Platelet Plug Formation
    1. Platelets adheres to exposed collagen
      1. By activating multiple factors needed to form fibrinogen bridges between glycoprotein IIb/IIa on adjacent platelets
    2. Adhesion--> Platelet activation --> Platelet aggregation= Platelet plug *Plug is unstable and needs fibrin
  2. Stage 2: Coagulation
    1. Production of fibrin to reinforce platelet plug
      1. Figure 55.2
      2. 2 Pathways
        1. Extrinsic (Tissue Factor Pathway)
          1. Activated by trauma to vascular wall--> Fibrin Formation
        2. Intrinsic (Contact Activation Pathway)
          1. Activated when blood makes contact with collagen that has been exposed as a result of trauma to blood vessel wall--> Fibrin Formation
        3. Both pathways go through factor conversions then converge at factor Xa Same final series of reactions occur in the pathways
          1. Factors Xa & Va convert prothrombin (II) to thrombin (IIa)
          2. Thrombin (IIa) converts fibrinogen to fibrin
          3. Clot formed that reinforces initial platelet plug
          4. Side note:
          5. Deep Vein Thrombosis (DVT) Occurs at bifurcations of deep veins If not treated, major risk is pulmonary embolism (PE) OR Afib causing stroke/MI