Hemostasis and Coagulation

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What enzyme converts phospholipids from the platelet membrane into arachidonic acid?

Platelet aggregation enzyme

Cyclooxygenase

Phospholipase A2 (correct)

Prostaglandin G2

Thromboxane synthetase

Which enzyme converts prostaglandins into thromboxane A2?

Prostaglandin G2

Phospholipase A2

Cyclooxygenase

Arachidonic acid converter

Thromboxane synthetase (correct)

What is the role of Ca21 in promoting platelet aggregation and vasoconstriction?

Inhibiting enzyme activity

Converting arachidonic acid

Released from the dense tubules (correct)

Preventing platelet aggregation

Activating phospholipase A2

How does aspirin function to decrease platelet activity?

By blocking cyclooxygenase enzyme Signup and view all the answers

Which factor initiates the intrinsic pathway of coagulation?

(9a, 8a, Ca, P) Signup and view all the answers

Which negative-charged surface activates the contact factor group in the coagulation system?

(In-vivo: collagen) Signup and view all the answers

What is the main role of ionized calcium in the coagulation process?

It binds to negatively charged phospholipid surfaces, allowing serine proteases to assemble the coagulation complexes. Signup and view all the answers

Which of the following is NOT a synonym for factor VII?

Antihemophilic factor A Signup and view all the answers

What is the effect of vitamin K on the coagulation factors with glutamic acid in their N-terminal?

Vitamin K converts the neutral charge of glutamic acid to a negative charge through gamma-carboxylation. Signup and view all the answers

What is the main function of the vitamin K-dependent coagulation factors?

They activate the coagulation cascade by converting prothrombin to thrombin. Signup and view all the answers

Which coagulation factor is also known as the 'Christmas factor'?

Factor IX (Christmas factor) Signup and view all the answers

How does the increase in levels of fibrinogen, prothrombin, and factor VIII relate to the coagulation process?

They are acute phase reactants, and their levels increase in response to inflammation, trauma, pregnancy, infection, and stress. Signup and view all the answers

Which serpin family member is a vitamin K-dependent plasma glycoprotein that increases the ability of ZPI to inhibit factor Xa 2000-fold?

Protein Z Signup and view all the answers

Which inhibitor is a nonspecific, heparin-binding serpin that can act as both an anticoagulant and a procoagulant depending on its target?

Protein C inhibitor Signup and view all the answers

Which member of the serpin family can inhibit factor XIa in a separate reaction that does not require protein Z, phospholipid, and Ca21?

ZPI Signup and view all the answers

What accelerates the inhibition of factor XIa by ZPI?

Heparin Signup and view all the answers

Which serpin family member is a potent inhibitor of factor Xa when in a complex with Ca21 and phospholipid?

ZPI Signup and view all the answers

Which serpin family member is capable of digesting plasma fibrinogen, factor V, factor VIII, and fibronectin when free in circulation?

a2-antiplasmin Signup and view all the answers

What is the primary function of heparan sulfate in the text?

Enhances the activity of antithrombin, a blood plasma serine protease inhibitor Signup and view all the answers

How does the pharmaceutical anticoagulant heparin resemble endothelial cell (EC) heparan sulfate?

Heparin has a similar structure and inhibitory activity when bound to antithrombin Signup and view all the answers

What is the initial response of the vascular system to injury according to the text?

Smooth muscle cells contract to minimize the flow of blood to the injured area Signup and view all the answers

What is the function of ADAMTS13 secreted from endothelial cells (ECs)?

ADAMTS13 cleaves large VWF multimers into shorter chains that support normal platelet adhesion Signup and view all the answers

What is the role of von Willebrand factor (VWF) when the vascular system is damaged?

VWF promotes coagulation by rolling and acting as a bridge that binds platelets to exposed subendothelial collagen Signup and view all the answers

What is the purpose of the exposed collagen-rich basement membrane/subendothelial connective tissue when the vascular system is damaged?

The exposed collagen-rich basement membrane promotes coagulation by activating platelets Signup and view all the answers

What is the primary role of the activated protein C-protein S complex?

Hydrolyzes and inactivates factors Va and VIIIa to slow or block thrombin generation and coagulation Signup and view all the answers

What is the approximate percentage of protein S that is free in the plasma?

40% Signup and view all the answers

What is the significance of protein S-C4bBP binding in inflammatory conditions?

It increases the risk of thrombosis by decreasing free protein S levels Signup and view all the answers

What is the condition called when neonates completely lack protein C?

Purpura fulminans Signup and view all the answers

What is the primary function of the protein C regulatory system?

To downregulate factors Va and VIIIa and slow or block coagulation Signup and view all the answers

What is the primary consequence of chronic acquired or inherited deficiency or mutations in the protein C or protein S pathways?

Increased risk of thrombosis Signup and view all the answers