overview of platelets and the coagulation system

1. Platelets,and CoagulationSystem
Fadel Muhammad Garishah, BSc

2. Thrombosis and Virchow’s
Triad

3. Platelets • Megakaryocytes’
daughters
• Actors of primary
thrombosis
• Activated and inhibited
by various stimuli
• Also involved in both
hemostatic and
immunity-inflammation
processes

4. Endothelial cells
• Lining of the vascular system
• Possessed various adhesion molecules for the adhesion of platelets, WBCs during
thrombosis and inflammation processes

5. Hemostasis – Thrombosis -
Fibrinolysis
http://www.hopkinsmedicine.org/hematology
/coagulation.swf

6. Platelet Activation

7. CoagulationCascadeand Fibrin
Polymerization

10. Fibrinolysis

12. Clinical Evaluation of
Thrombosis
• Clotting Time
• Bleeding Time
• Prothrombin Time
• Activated Partial Thromboplastin Time

13. Bleeding time
• Platelet functions to form clot
• Wound in superficial area -> normally 1-9 min stops
• Prolonged: platelet dysfunction, vWD, anticoagulant use,
uremia, liver failure, leukemias, MDS

14. Thrombin time
• Assess fibrin formation in plasma
• TT time < 20 seconds
• Shortened: hereditary, DIC, multple myeloma

15. Prothrombin Time
• Extrinsic factors and final common pathway
• Factor II, V, VII, X
• Adding Ca2+ and thromboplastin (activator) to blood sample,
and then measure the time
• PT 9,5 – 13,5 seconds
• INR < 1.
• Prolonged PT: warfarin use, def vit K, liver disease, deficiency
of F II, VIII, V, X, DIC, fibrinogen abnormalities, heparinization

16. PartialThromboplastinTimeorActivatedPartial
ThromboplastinTime
• Intrinsic coltting factors etc
• aPTT additional activator that speeds up PTT
• aPTT 30-40 seconds
• PTT 60 – 70 seconds
• Prolonged causes: Def F VIII, IX, XI, XII,
Fitzgeralnd/prekalikrein, vWD, hypofibrinogenemia, liver
cirrhosis, def vit K, , DIC, heparinization, coumarin inhibition
FI, IX and X
• Shortened: early DIC, cancers, hemorrhage,