Lecture 8

Question 1

What is the first event that will occur immediately after an injury occurs?

Answer 1

Vascular spasm- results in a reduction in blood flow to the site- occurs immediately after vasoconstriction and should be proportional to the degree of trauma. Generally, can last anywhere from a few minutes to a couple of hours.

Question 2

State the four main events of the primary platelet response:

Answer 2

1. ) The binding of VWF to the sub-endothelial matrix
2. ) Adhesion
3. ) Activation
4. ) Amplification

Question 3

Briefly describe what happens in the adhesion step:

Answer 3

Platelets bind to the exposed sub-endothelial matrix proteins with the aid of adhesion factors (e.g VWF)

Question 4

Briefly describe what occurs in the activation step of the primary platelet response:

Answer 4

1. ) Platelets touch the glyco-proteins they become activated
2. ) Go from being a pancake shape to an octopus shape with multiple legs
3. ) When they are activated degranulation occurs- all of the contents are released into the external environment- basic function is to attract more proteins to the site
4. ) Final part involves the activation of the GPIIIB/IIa receptor

Question 5

Briefly explain what occurs in the amplification stage of the primary platelet response:

Answer 5

More and more platelets accumulate at the site of the damage drawn by the degranulation of the platelets

Question 6

What is the main aim of the secondary platelet response?

Answer 6

Main aim is to convert fibrinogen into fibrin that forms a mesh

Question 7

Briefly describe what occurs in the secondary platelet response:

Answer 7

Small amount of thrombin produces much more thrombin and a cascade model evolves. Amplification stage occurs on the surface of activated platelets.