Exam 2 -- Hematology #3 Flashcards
How are platelets shaped?
Biconvex
What is the lifespan of a platelet?
About 8 days
What is the function of platelets?
Repair vascular endothelium, prevent excessive blood loss
What factors are involved in platelet activation?
Collagen, thrombin, ADP, epinephrine
What factor is involved with platelet adhesion?
Von Willebrand Factor
What factors stimulate platelet secretion?
ADP, serotonin, fibrinogen, thromboxane A2, growth factors
The clotting cascade, in a basic way, involves thrombin converting fibrinogen into fibrin. What are two cofactors important in this cascade?
Calcium and vitamin K.
Damage to the tissue and subsequent release of coagulation factors from the tissue itself is part of the __________ pathway (intrinsic/extrinsic)
Extrinsic
Damage to the blood vessel endothelium and subsequent release of coagulation factors is part of the ______________ pathway (intrinsic/extrinsic)
Intrinsic
All of the factors involved in the coagulation cascade are synthesized in the liver except one. Which is it, and where is it synthesized?
Von Willebrand Factor, which is synthesized in the blood vessel lining
What factor is incorporated into a clot for later fibrinolysis (clot breakdown)?
Plasminogen; it breaks down the clot after being converted to plasmin
Prothrombin time (PT) and Activated partial thromboplastin time (aPTT) are sometimes included in CBC and are tests that can be done to test the coagulation pathways. Which of these tests is for the intrinsic pathway? Which is for the extrinsic pathway?
PT is for the extrinsic pathway; aPTT is for the intrinsic pathway
What is a normal value for a PT?
~15 seconds
In order to try and standardize PT findings, the international normalized ratio (INR) was developed. What is a normal INR?
1
What is a normal value for an aPTT?
30-50 sec
Bleeding disorders can include what types of signs/symptoms?
Petechiae (broken capillaries), purpura (larger broken capillaries), ecchymosis (bruise), epistaxis (nosebleed), menorrhagia (heavy menstrual period), subconjunctival hemorrhages, gum bleeding.
Vitamin C (aka ascorbic acid) plays what important roles?
Aids in collagen synthesis, reduces free radicals, maintains plastaglandin/prostacyclin balance
Vitamin C deficiency (aka scurvy) takes how long to develop? How quickly can it resolve if the deficiency is resolved?
4-8 months to develop, days to weeks to resolve
What is the recommended daily intake of vitamin C?
75 mg