Hemostatic Function Flashcards
Hemostasis
Stoppage of bleeding by Vc, formation of platelet plug, formation of insoluble fibrin clot and activation fibrinolytic system that dissolve clot and restore blood flow to injured site
Bleeding time
Definition: time needed to stop bleeding without clot formation
Time: 1-3 minutes
Depends on: vasoconstriction / spasm
Platelet count and viability
Bleeding time
Prolonged in: purpura caused by vascular wall defect like in scurvy vitamin c deficiency
Thrombocytopenia less than 30,000 mm 3
Thrmobasthenia
Procedure: sterilize and prick finger with lancet
Blood wipe every 15 seconds with filter paper
Record time needed till bleeding time
Coagulation Time
Definition: Time needed to form clot
Time: 3-10 minutes
Depends on: Clotting factors
(Liver function , Vit K)
Coagulation time
Prolonged in: Hemophilia (A ↓VIII or
B ↓IX or C ↓XI)
• Liver disease (cirrhosis)
• ↓ vit K as in new born→(↓formation of
2,7,9,10)
• Patient receiving heparin
Procedure: Sterilize, Prick finger with lancet.
- Draw blood into non-heparinized capillary tube.
- hold the tube in horizontal position
Every 30 sec., break off small piece (0.5 cm)
of tube until fibrin threads is formed & visible
& span a gap of 5 mm between the broken ends
Theoretical questions
Platelet reactions: Adhesion, activation, release, aggregation, procoagulant activity, fusion
Enumerate pathological variations in platelet count: ↑: thrombocytosis, ↓: thrombocytopenia
Theoretical questions
Precautions of bleeding time: Sterilization
Don’t touch finger when wiping blood to avoid displacement of platelet plug
Platelet count: 300000/mm3
Theoretical questions
Purpura: subcutaneous petechial hemorrhage due to
Mechanism of coagulation: intrinsic & extrinsic pathways
Theoretical questions
Explain difference between bleeding & clotting time: clot formation
Theoretical questions
Types of anticoagulant: heparin, dicumarol
