L8 : Blood clotting and its disorders

Question 1

what stops the coagulation cascade ?

Answer 1

as soon as enough fibrin has been formed to stabilize the clot , Antithrombin and Proteins C and S stop the cascade by inactivating factor V and VIII

Question 2

What limits clot to the site of injury and prevents its spread to nearby normal tissue ?

Answer 2

normal endothelium of nearby vessel wall secrets both Prostacyclin and nitric oxide

Question 3

how are blood clots lysed after the injury has healed ?

Answer 3

fibrinolysis occurs a few days after the clot has stopped bleeding , the injured tissue and vascular endothelium slowly release a powerful activator called tissue plasminogen activator. t-PA eventually converts plasminogen to plasmin which cleaves the fibrin surrounding the clot leaving little fragments of clot that simply wash away.

Question 4

platelet degranulation releases ____

Answer 4

platelet deriver growth factor ( PDGF) that stimulates smooth muscle cells and fibroblasts to divide and rebuild wall

Question 5

what are the substances released by activated platelets ?

Answer 5

serotonin : vasoconstriction

vWF: platelet adhesion

thromboxane A2 ADP:increase platelet aggregation

PDGR; growth repair of the vessel wall

Question 6

what would a defect in blood vessel walls result in?

Answer 6

scurvy

Question 7

what would a defect in number or function of platelets result in ?

Answer 7

purpura

Question 8

what would a defect in clotting factors result in ?

Answer 8

hemophilia