Week 7 - Bleeding and Clotting Flashcards
What is hemostasis?
- When we have an injury, the body must have a way to stop losing blood while still maintaining perfusion to the tissues
Why is perfusion important to the body?
- needed to sustain life, supply oxygen and nutrients to tissues
What do we need in our body to form clots? (3)
- platelets
- clotting factors
- we need these 2 in the blood, working together to form the mature and functional fibrin clot
What are thrombocytes? (2)
- platelets
- are blood cells made in the bone marrow and stored in the spleen
Where are clotting factors made?
liver
Bone marrow producing cells diagram
What occurs in the extrinsic pathway in the clotting cascade? (2)
- collagen exposed in the vessels activate the clotting
- generally protective
What causes the extrinsic pathway clotting cascade to occur? (2)
- external cellular injury (trauma, laceration)
- bacteria or inflammation can also trigger it
What causes the intrinsic clotting pathway to occur? (2)
- no trauma, but internal conditions trigger it
- less protective and more problematic
Why is the intrinsic pathway dangerous? or it might be what causes it (4)
- venous stasis
- lack of blood flow
- plaques in vessels
- too many clotting factors
The end product of the clotting cascade is a _____ ____
fibrin clot
Which labs measure blood clotting? (4)
- Activated partial thromboplastin (apTT)
- International normalized ratio (INR)
- Prothrombin time (PT)
- Platelet count
What is the purpose of activated partial thromboplastin (aPTT)? (2)
- assessment of intrinsic cogulation by measuring factors I, II, V, VIII, IX, X, XI, XII
- normal values 25-35 sec (increased time means it is longer to clot
What is the purpose of the international normalized ratio (INR)? (3)
- standardized way of reporting PT
- compares pt with a control value
- normal values 0.8-1.2
What is the purpose of prothrombin time (PT)?
assessment of extrinsic coagulation by measurement of factors I, II, V, VII, and X
- normal value 11-16 sec
