cardiovascular

Question 1

What are the 5 steps of Platelet plug formation?

Answer 1

Injury
Exposure
Adhesion
Activation
Aggregation

Question 2

Describe Injury

Answer 2

Nerves and smooth vessels detect injury=Triggers contractions and reduced blood flow
NO and Prostaglandin secretion stops,Endothelin-1 released causes VASOCONSTRICTION

Question 3

Describe Exposure

Answer 3

Damage to endothelial exposes collages which VWF binds to

Question 4

Describe adhesion

Answer 4

Platelets bind to VWF via GP1B receptor at site of injury

Question 5

Describe Activation

Answer 5

Change to shape and platelets become activates.Positive feedback=more platelets activated

Question 6

Describe aggregation

Answer 6

GPIIB+GPIIIA bind to fibrinogen.This links platelets together

Question 7

Coagulation Cascade

Answer 7

Intrinsic pathway=Internal damage to blood vessels and less common
Extrinsic pathway=Extravascular trauma and more common

Question 8

Extrinsic pathway

Answer 8

Tissue factor(Factor III) binds to factor VII creating TF-VIIA complex
This activates factor X into active form Factor Xa which triggers formation of thrombin

Question 9

Intrinsic Pathway

Answer 9

Factor XII activated when in contact with negatively charged collagen which triggers cascade
Factor IX combines with Factor VIII to form an enzyme complex that activates factor X, which along with factor Va, stimulates the production of thrombin.

Question 10

Common pathway

Answer 10

Activated Factor X causes inactive enzyme prothrombin(Factor II) to convert into active form thrombin(Factor IIa) via prothrombinase
Thrombin converts soluble fibrinogen(Factor I) into insoluble fibrin strands stabilised by factor XIII

Question 11

Fibrinolytic pathway

Answer 11

Blood clots need to be broken down so plasminogen is converted to plasmin via plasminogen activators–>Breaks fibrin–>Breaks blood clot

Question 12

Where are clotting factors produced?

Answer 12

Liver

Question 13

Vitamin k dependent factors

Answer 13

X
IX
VII
II
(1972)