Thrombocytes Flashcards
Where do thrombocytes originate?
Bone marrow
Where is thrombopoietin produced?
In the liver and kidney
What is thrombopoietin?
A glycoprotein hormone which regulates the production of platelets
What is endomitosis? (aka endoreduplication)
Nuclear division without cytoplasmic division
How many times can a megakaryocte divide during development?
2-5 times
What is a proplatelet?
The long extension on a megakaryocyte
How long do thrombocytes remain in circulation?
7-10 days
As platelets age, do they become more or less functional?
Less
At any one time, about 2/3 of all platelets in the body are found in circulation. Where is the other 1/3?
The spleen
What causes the body to fragment and release platelets?
Contraction of the spleen due to epinephrine release
What is the main function of a thrombocyte?
Hemostasis
Thrombocytes release thrombospondin during inflammation and infection. What does thrombospondin do?
It causes bacteria to adhere to the thrombocytes
Endothelial injury exposes ________, which attracts platelets
Collagen
What helps to mediate plate adhesion?
Von Willabrand factor
____ in combination with ADP recruit more platelets to form a plug
TXA2
What chemical activates the intrinsic coagulation system?
PF-3 (platelet factor 3)
TXA2 and PF-3 are both chemicals released during hemostasis. Where is each released from?
TXA2 - from the damaged tissue
PF-3 - from a platelet once it is stuck to the area being repaired
How many thrombocytes are normally present in 1 microliter of blood?
200,000-400,000 in an absolute count
How low must the thrombocyte count fall for spontaneous bleeding to occur? (in thrombocytes/microliter)
What is the difference between thrombocytopenia and thrombocytopathia?
Thrombocytopenia is decrease in platelet number, and thrombocytopathia is decrease in platelet function
What is thrombocytosis?
Increased platelet count
What are the 3 causes of thrombocytosis?
Essential thrombocythemia: too many platelets are being produced
Secondary thrombocytosis: the body is reacting to something
Physiological thrombocytosis: a physiologic occurrence in the body is causes an increase in platelets
What are the clinical signs of thrombocytopenia/thrombocytopathia?
Petechia, melena/hematochezia, hematuria, epistaxis, cutaneous ecchymose, and prolonged or excessive bleeding
