• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/27

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

27 Cards in this Set

  • Front
  • Back

What type of cells produce anticoagulants?

Anti-coagulants are produce by Endothelial cells.




i.e released by the vessel wall lining

What are the 6 anticoagulants released by the endothelial cell wall?

Heparins


TFPI (tissue factor pathway inhibitor)


Thrombomodulin


Nitric oxide


Prostacyclin

What happens when there is an injury?

Bleeding at the site of injury




A clot is formed, bleeding stops due to: Platelets, Von Willebrand factor, coagulation factors




The clot remains at the site of the injury not everywhere due to the natural anticoagulants released by the endothelial cells




The clot later vanishes: Due to the fibrinolytic system.

Describe how the platelets stick to the endothelial surface after injury and form a platelet plug

vWF, Collagen and Tissue factor sit in the sub endothelium and are only exposed when there is damage to the top layer of endothelium.




When vWF, collogen and tissue factor are exposed the platelets are then attracted to stick to the exposed surface.




As the platelets gather this creates a platelet plug

What are the chemicals inside platelets that are known as alpha granules and aid the clotting process?

The alpha granules store vWF and Thrombin.




(also actin and myosin inside platelet which are stimulated to contract reinforcing the platelet plug)




*This means vWF lies within the platelets and the subendothelium*

What is the role of Von Willerbrand factor in blood clotting?

vWF plays a major role in blood coagulation:




Binds to platelets


Binds to factor VIII


Binds to collogen




*basically like a big glue that binds to all the platelets and aids aggregation*

What substance in the blood stream ensures that the clot remains confined to the site of the injury?

Natural anti-coagulants



What is the most powerful natural anticoagulant?

Anti-Thrombin is the most power natural anticoagulant.




*patients with deficiencies in antithrombin are at much higher risk of PEs and DVTs*

What is the substance within platelets that allow them to contract and aggregate?

Actin and Myosin inside the platelets allow them to contract and aggregate.

What are the platelets role in haemastasis?

Adhere, activation and aggregation




They provide a phospholipid surface for coagulation.

What happens at the end of the clotting cascade to seal of the platelet plug and protect it?

To seal off the coagulation of platelets.




Prothomibin turns into Thrombin which inturn activates Fibrinogen to turn into Fibrin.




It is this fibrin which forms a protective web over the clot.

Once platelets have begun to gather on the surface of an endothelial injury, what chemical is responsible for further attracting more and more platelets?

Thrombin acts to attract even more platelets.




Thrombin then goes on to stimulate fibrin which forms the mesh stabilising the clot.

What is the main cause of an arterial clot forming?

Rupture of an atherosclerosis plaque.






*arterial clots are very platelet rich*

What is the main cell constituency of venous blood clots?

Mainly clots in the veins consist of Fibrin and RBCs

Once the anti-thrombin has done its job and prevented the surrounding area from clotting, the clot itself can now be removed.




At this point Fibrinolysis starts to kick in and remove the original clot.




What is the name of the chemical that the endothelium releases in order to begin the process of clot busting?

The endothelial cells release TPA (tissue plasminogen activator) which works to release Plasminogen and thus Plasmin.

What is the role of Plasmin in the breakdown of clots?

Plasmin is the enzyme responsible for Fibrinolysis - i.e. degradation of clots

What is the role of tissue factors in producing blood clots?




e.g Factor VIII

Tissue factors work by triggering the cascade which produces Thrombin and thus Fibrin.




Therefore without tissue factors there is no Fibrin to cover the clots and so they stay put.

What is the chemical released by fibrin clots as it degraded by Plasmin?

As plasmin works away at the Fibrin clots it releases FDPs (fibrin degradation products).




These products contain D-Dimers which are searched for in blood tests to detect internal tissue injury.

What enzyme involved in platelet aggregation is blocked by the anticoagulant Aspirin?

Aspirin works by blocking COX (cycloxygenase) -






COX is essential enzyme in Thrombin production and so if it is blocked then clotting is blocked.

What receptor does Clopidogrel bind to to stop platelet signals?

Clopidogrel works by binding to ADP receptors and thus stopping the signals which call for more platelets.

Which tissue factors in the clotting cascade are inhibited by the actions of warfarin?

Factor IX, X, VIII and Prothombin are all inhibited by Warfarin and so the production of Thrombin and thus Fibrin is reduced.




Warfarin is best for venous thrombosis e.g AF, DVTs and PE.




*reverse the effects of warfarin using Vit K*

What chemicals and tissue factors are inhibited by Heparin?

Heparin works by combining with antithrombin (natural anticoagulant) and switching off Thrombin.




It also switches of Factor Xa






*+++ Heparin enhances the effects of anti- thrombin +++*

What factor is responsible or the conversion of Prothombin to Thrombin?

Factor Xa is responsible for the conversion of Prothombin to Thrombin

What is the name of the enzyme which converts fibrinogen to fibrin?

Thrombin

Which factor is inhibited by Rivaroxaban to stop clot formation?

Rivaroxaban works by inactivating factor X.




Therefore the whole cascade cant occur and Prothombin isnt activated.

The active site of which enzyme in the clotting process does Dabigatran/Bivalirudin work on to prevent clot formation?

Dabigatran/Bivalirudin works directly on the active site of Thrombin which stops the conversion of Fibrinogen to Fibrin.

Explain the clotting cascade from the first cut in the endothelium?

Cut exposes sub endothelium


-


Sub endothelium releases vWF, Collogen and Tissue factors


-


Platelets are attracted over to vWF because they themselves have vWF and also mycin and actin which help them change shape and clot better


-


Tissue factors (X and VII mainly) gets to work by triggering Prothrombin to change into Thrombin


-


Thrombin is the enzyme which converts Fibrinogen into Fibrin


-


Fibrin then forms a big meshy net over the platelets that have aggregated


-


Whilst the whole time natural anti-thrombin is protecting the surrounding blood stream from becoming clotted


-


Once the clot is ready to be removed endothelial cells release TPA (tissue plasminogen activators)


-


TPAs work to trigger Plasmin release


-


Plasmin then engages Fibrinolysis


-


Fibrinolysis in turn releases FDP (Fibrin degradation products) which contain D-Dimer and thus signal tissue damage in blood results.