Normal Hemostasis and Coagulation

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What is the primary phase of normal hemostasis?

Platelet adhesion and aggregation
Activation of coagulation enzymes
Response to vascular injury (correct)
Vasoconstriction and vascular spasm

Which of the following is NOT a component of the normal hemostasis process?

Platelet aggregation
Coagulation enzyme activation
Fibrinolysis (correct)
Vasoconstriction

What is the primary function of normal hemostasis?

To promote excessive bleeding
To maintain blood in a fluid state within normal vessels (correct)
To prevent clot formation under any circumstances
To facilitate the transport of oxygen and nutrients

Which of the following statements about normal hemostasis is TRUE?

It involves the interaction of vasoconstriction, platelet adhesion and aggregation, and coagulation enzyme activation (C) Signup and view all the answers

Which of the following is NOT a part of the normal hemostasis process?

Vasodilation (A) Signup and view all the answers

Which of the following statements about microtubules in platelets is correct?

They are thick, circumferential bundles that reside just within the plasma membrane, maintaining the platelet's discoid shape. (B) Signup and view all the answers

Which of the following statements about alpha granules in platelets is incorrect?

They contain adenosine diphosphate (ADP) and adenosine triphosphate (ATP). (D) Signup and view all the answers

What is the primary function of the dense granules in platelets?

To store and release substances that promote vasoconstriction and platelet activation. (C) Signup and view all the answers

What is the approximate number of alpha granules found in each platelet?

50 to 80 (C) Signup and view all the answers

Which of the following statements about the contents of alpha granules is correct?

They contain proteins that participate in secondary hemostasis (coagulation). (B) Signup and view all the answers

What is the half-life range of Factor XII (Hagemann Factor)?

84-70 hours (D) Signup and view all the answers

Which factor is associated with Hemophilia C or Rosenthal syndrome?

Factor XI (B) Signup and view all the answers

Which of the following statements is true regarding Factor XIII (Fibrin Stabilizing Factor)?

It can be tested in serum. (B) Signup and view all the answers

What is the mean plasma concentration of Factor XI?

3 mg/dL (D) Signup and view all the answers

Which of the following statements is true about Prekallikrein (PK)?

It is partially adsorbed by $\mathrm{BaSO_4}$ and Celite but not by $\mathrm{Al(OH)_3}$. (B) Signup and view all the answers

Which of the following is NOT a fibrinolytic property of the endothelial cells?

Releasing plasminogen activator inhibitors (PAIs) (D) Signup and view all the answers

What is the primary role of the intact vascular endothelium in preventing thrombosis?

Inhibiting platelet aggregation and coagulation activation (D) Signup and view all the answers

Which of the following statements about the endothelial cells' role in hemostasis is FALSE?

Endothelial cells release tissue factor, which increases the catalytic function of factors IXa and Xa. (C) Signup and view all the answers

Which of the following statements best describes the role of collagen and tissue factor in thrombosis?

Collagen promotes platelet adhesion, while tissue factor activates coagulation. (C) Signup and view all the answers

Which of the following statements best describes the anticoagulant properties of the intact vascular intima?

It inhibits platelet aggregation, prevents coagulation activation, and enhances fibrinolysis. (A) Signup and view all the answers

Which of the following statements about the endothelial cells' role in hemostasis is TRUE?

Endothelial cells release tissue-type plasminogen activator (t-PA) to degrade fibrin and dissolve thrombi. (C) Signup and view all the answers

Which of the following correctly describes the role of TXA2 in platelet activation?

TXA2 suppresses adenylate cyclase, reducing cyclic AMP concentration and allowing the release of ionic calcium from the DTS, which supports actin microfilament contraction and platelet activation. (D) Signup and view all the answers

Which of the following correctly describes the role of the Inositol Triphosphate-Diacylglycerol (IP3-DAG) pathway in platelet activation?

G-protein activates phospholipase C, which cleaves membrane phosphatidylinositol 4,5-biphosphate to form IP3 and DAG. IP3 promotes the release of ionic calcium from the DTS, which activates actin microfilament contraction, while DAG activates phosphokinase C, triggering the phosphorylation of pleckstrin and regulating actin microfilament contraction. (B) Signup and view all the answers

Which of the following statements correctly describes the role of platelet adhesion receptors in platelet activation?

GP Ib/IX/V, GP VI, and 21 (GP Ia/IIa) receptors bind to collagen, causing the platelet to become firmly attached to the damaged surface, where it subsequently loses its discoid shape and spreads. (A) Signup and view all the answers

Which of the following correctly describes the role of TXA2 and ADP in platelet activation?

TXA2 and ADP are secreted from the platelet to the microenvironment, where they activate adjacent platelets through their respective receptors and provide inside-out activation of IIb3 (GP IIb/IIIa), which assists in platelet aggregation. (B) Signup and view all the answers