Blood stuff

Question 1

An important early step in hemostasis is vasoconstriction of the damaged vessel. Platelets play a key role in this initial vasoconstriction by release of what substances?

Answer 1

The vascular contraction is a result of autonomic nervous system reflexes and the release of thromboxane A2 and ADP from platelets

Question 2

The endothelium releases many procoagulant factors following vascular injury. Name two key procoagulants released by the endothelium

Answer 2

tissue factor and von willebrand factor

Question 3

In addition to its role in early vasoconstriction, thromboxane A2 plays a key role in activation and aggregation of platelets, Describe the actions of txa2 in activation and adhesion of platelets.

Answer 3

Once platelets adhere they are activated by a complex series of steps including release of ADP and thromboxane A2. Adenosine diphosphate (ADP) and txa2 are ligands for G protein coupled receptors. General transduction pathways ultimately leading to expression of GPIIB/IIIA receptors on the platelet surface. txa 2 appears to amplify the signal and action of more potent platelet agonists such as thrombin and ADP.