M3 L5a: Antithrombotic agents

Question 1

hemostasis

Answer 1

process that retains blood within the vascular sys

Question 2

thrombosis

Answer 2

formation of a thrombus (blood clot) within a blood vessel

Question 3

steps of hemostasis

Answer 3

injury of blood vessel -> loss of vascular integrity ->

series of 4 events:
1. vasoconstriction
2. platelet activation
3. blood coagulation and clot formation
4. fibrinolysis

Question 4

vasoconstriction

Answer 4

decreased blood flow to injured vessel -> decreased blood loss

Question 5

what is platelet activation

Answer 5

• platelets adhere to collagen fibrils on the injured vessel with the help of vWF
• platelets aggregate to each other under the effect of thrombin and fibrinogen -> platelet plug
• once activated, platelets release chemical mediators as adenosine diphosphate (ADP) and thromboxane A2 (TxA2) to activate more platelets

Question 6

blood coagulation and clot formation

Answer 6

• activation of coagulation factors -> coagulation pathway
• platelet plug turns into more stable blood clot (fibrin network + blood cells)

Question 7

fibrinolysis

Answer 7

• enzymatic process that dissolve the fibrin clot
• occurs concomitantly w coagulation
• controls the size and spread of the fibrin clot
• carried out by the enzyme plasmin

Question 8

natural anticoagulants

Answer 8

1. antithrombin (AT)
   nature: serine protease inhibitor
   activated by: heparin
   inactivates: factors 2a and 10a
2. protein C
   nature: vitamin K- dependant protein
   activated by: thrombin
   inactivates: factors 5a and 8a

Question 9

abnormal hemostasis

Answer 9

• bleeding disorders
• thromboembolic disease

Question 10

3 bleeding disorders

Answer 10

1. vascular defects (ex: vasculitis)
2. platelet defects (ex: thrombocytopenia)
3. coagulation factors defects (ex: hemophilias)

1&2 are purpura

Question 11

hemophilias

Answer 11

• bleeding disorder
• congenital or acquired (emphasis on congenital)
• due to coagulation factors deficiency: hemophilia A and factor deficiency V111 (main) but also B 1X, C X1
• bleeding: after trauma or spontaneously

Question 12

thromboembolic disease

Answer 12

• group of diseases due to hypercoagulable states
  ex: deep vein thrombosis (DVT), pulmonary embolism (PE), CAD
• treated by antithrombotic agents