Platelets and Coagulation Cascade Flashcards
What type of Cells are Platelets? What form do they circulate in? Where do they originate from?
Anucleate cells
Circulate in inactive form
Originate from megakaryocytes
4 cells involved in the formation of a Platelet and what happens between each stage?
Myeloid stem cell–> Megakaryoblast (Differentiation)
–> Megakaryocyte (Endomitosis)
–> Platelet (Membrane blebbing)
What are the two pathways involved in the coagulation cascade?
Intrinsic and Extrinsic pathways
Explain the Intrinsic pathway of the coagulation cascade
Surface contact of blood activates factor XII
activated factor XII activated factor XI
activated factor XI activates factor IX
activated factor IX activates factor X along with factor VII, phospholipid and Ca2+
What does tissue damage cause to be released in the Extrinsic factor of the coagulation cascade? What does this activate?
Causes Tissue factor to be released
Activated VII
What is activated by the products of both the Intrinsic and Extrinsic pathways?
X–> Xa
Explain the common pathway of the Coagulation cascade starting with Xa (3 steps)
Xa converts Prothrombin into thrombin
Thrombin converts fibrinogen into fibrin and activates XIII
Fibrin along with XIIIa forms a stable fibrin clot
Draw out the full coagulation cascade
Which Factors are involved in the Intrinsic pathway? In order?
12, 11, 9, 7, 10
What initiates the beginning of platelet plug formation? What receptors are involved and what do they bind to?
Exposed collagen
GPVI receptors on platelet bind to exposed collagen directly
Gp2b/IIIa receptors bind to Von Willebrand Factor
What two types of granules do platelets contain?
Electron Dense and alpha granules
What do the Electron dense granules release in platelets? (4)
ADP, ATP, seretonin and Calcium
What reactions are involved in the activation of platelets?
ADP acts on P2Y1 and P2Y12
Thrombin acts on PAR-1 and PAR-4
Thromboxane A2 acts on TP alpha
