1.
Which of the following contains exposed collagen to which platelets bind during vascular injury?
Correct Answer
B. Subendothelial cells
Explanation
During vascular injury, the subendothelial cells are exposed, which contain collagen. Collagen is a protein that acts as a binding site for platelets. When platelets come into contact with exposed collagen, they bind to it and initiate the formation of a blood clot to stop bleeding. Therefore, subendothelial cells containing exposed collagen are the site where platelets bind during vascular injury.
2.
Which of the following is an INHIBITOR of platelet adhesion and aggregation?
Correct Answer
A. Prostacyclin
Explanation
Prostacyclin is an inhibitor of platelet adhesion and aggregation. It is a prostaglandin that is produced by endothelial cells and acts to prevent platelets from sticking together and forming clots. Prostacyclin also causes vasodilation, which helps to maintain blood flow and prevent clot formation. Therefore, it is a natural inhibitor of platelet function and plays an important role in maintaining normal blood circulation.
3.
Platelet adhesion, the process of platelets binding to exposed subendothelial tissue after vascular injury, is primarily mediated by?
Correct Answer
E. Von Willebrand Factor
Explanation
Platelet adhesion is the process of platelets binding to exposed subendothelial tissue after vascular injury. This process is primarily mediated by Von Willebrand Factor (VWF). VWF is a large multimeric glycoprotein that is secreted by endothelial cells and circulates in the blood plasma. It plays a crucial role in platelet adhesion by binding to both platelets and exposed subendothelial collagen. This interaction facilitates the initial attachment of platelets to the site of injury, leading to the formation of a platelet plug and initiation of the clotting cascade.
4.
____________ is insoluble, while its precursor ____________ is soluble.
Correct Answer
B. Fibrin, Fibrinogen
Explanation
Fibrinogen is soluble, while its precursor fibrin is insoluble. Fibrinogen is a soluble protein found in the blood plasma, and it is converted into fibrin during the clotting process. Fibrin forms a mesh-like structure that helps in the formation of blood clots to stop bleeding. The insolubility of fibrin allows it to form a stable clot, preventing further blood loss.
5.
Which of the following is a protease responsible for converting fibrinogen to fibrin?
Correct Answer
C. Thrombin
Explanation
Thrombin is a protease responsible for converting fibrinogen to fibrin. Fibrinogen is a soluble protein that is converted into insoluble fibrin during blood clotting. Thrombin cleaves fibrinogen at specific sites, leading to the formation of fibrin molecules that polymerize and form a meshwork, which is essential for blood clot formation. Thrombin also has other important roles in the coagulation cascade, including the activation of other clotting factors and platelets.
6.
Which of the following is the point where extrinsic and intrinsic pathways converge?
Correct Answer
B. Xa
Explanation
Xa is the point where extrinsic and intrinsic pathways converge. This is because Xa is the activated form of factor X, which is a key component in both pathways. In the extrinsic pathway, factor X is activated by factor VIIa, while in the intrinsic pathway, factor X is activated by factor IXa. Therefore, Xa serves as the common point where these two pathways come together.
7.
Which of the following is NOT correlated with Factor Xa?
Correct Answer
C. Inhibition of Factor VII to VIIa
Explanation
Factor Xa is not correlated with the inhibition of Factor VII to VIIa. Factor Xa is a key component in the coagulation cascade and plays a crucial role in the activation of prothrombin to thrombin. It is the activated form of Factors X and is involved in the convergence of the extrinsic and intrinsic pathways. However, it does not have a direct correlation with the inhibition of Factor VII to VIIa.
8.
Which of the following is NOT part of the tenase complex?
Correct Answer
E. Factor VIIa
Explanation
The tenase complex is a key component of the coagulation cascade and is responsible for the activation of factor X. It consists of factor VIIIa, factor IXa, and calcium ions (Ca2+). Factor VIIa, on the other hand, is part of the extrinsic pathway and forms the initiation complex, not the tenase complex. Therefore, factor VIIa is not part of the tenase complex.
9.
Which of the following initiates the extrinsic pathway of the clotting cascade?
Correct Answer
A. Factor III (Tissue Factor)
Explanation
Factor III, also known as Tissue Factor, initiates the extrinsic pathway of the clotting cascade. This pathway is activated when there is damage to the blood vessel wall, and it involves the release of Tissue Factor from the damaged tissue. Tissue Factor then forms a complex with Factor VII, which activates Factor X and leads to the formation of a blood clot. Factors VIII and IX are part of the intrinsic pathway, which is activated by contact between blood and a foreign surface.
10.
Factor II is known as _____________, while Factor IIa is known as __________.
Correct Answer
D. Prothrombin, thrombin
Explanation
Factor II is also known as prothrombin, while Factor IIa is known as thrombin. Prothrombin is an inactive precursor protein that is converted into thrombin through a series of enzymatic reactions. Thrombin is a key enzyme in the coagulation cascade that plays a crucial role in the formation of fibrin, which is the insoluble protein responsible for blood clot formation. Therefore, the correct answer is Prothrombin, thrombin.
11.
Which of the following is NOT inhibited by heparin?
Correct Answer
F. Fibrin
Explanation
Heparin inhibits the coagulation cascade by binding to antithrombin III and enhancing its activity. This leads to the inhibition of several factors involved in the coagulation process, including factor XIIa, factor XIa, factor IXa, factor Xa, and thrombin. However, heparin does not directly inhibit the formation of fibrin, which is the end product of the coagulation cascade. Fibrin is formed when thrombin cleaves fibrinogen, leading to the formation of fibrin monomers that polymerize to form a stable clot.
12.
Which of the following is NOT an inhibitor of thrombin?
Correct Answer
E. All are inhibitors of thrombin
Explanation
All of the options listed in the question are inhibitors of thrombin. Thrombin is a crucial enzyme involved in the blood clotting process, and these inhibitors play a role in regulating its activity. Heparin is a well-known anticoagulant that directly inhibits thrombin. Alpha2-macroglobulin and Alpha1-antitrypsin are both protease inhibitors that can also inhibit thrombin. Heparin cofactor II is a protein that specifically enhances the inhibitory activity of heparin against thrombin. Therefore, none of the options listed are NOT inhibitors of thrombin.
13.
Which of the following is primarily responsible for degradation of fibrin clots?
Correct Answer
A. Plasmin
Explanation
Plasmin is primarily responsible for the degradation of fibrin clots. Plasmin is an enzyme that is derived from its inactive precursor, plasminogen. When plasminogen is activated, it converts fibrin, the protein responsible for clot formation, into soluble fragments, resulting in the breakdown of the clot. Thrombin and prothrombin are involved in the clotting process, while Factor III is not directly involved in clot degradation.
14.
Hemophilia A is classic hemophilia. It is a disease referring to the inability to clot blood. Which of the following is deficient in this X-linked recessive disorder?
Correct Answer
B. Factor VIII
Explanation
Hemophilia A is a disease characterized by the inability to clot blood. It is an X-linked recessive disorder, meaning it is caused by a mutation on the X chromosome. The correct answer is Factor VIII, as this clotting factor is deficient in individuals with Hemophilia A. Factor VIII plays a crucial role in the clotting cascade, helping to form a stable blood clot. Without enough Factor VIII, blood clotting is impaired, leading to prolonged bleeding and easy bruising.
15.
Hemophilia B results from a deficiency of which clotting factor?
Correct Answer
C. Factor IX
Explanation
Hemophilia B is a genetic disorder that results from a deficiency of clotting factor IX. This clotting factor is necessary for the formation of blood clots to stop bleeding. Without enough factor IX, individuals with hemophilia B experience prolonged bleeding and have difficulty forming clots. This condition is also known as Christmas disease, named after the first patient diagnosed with it.
16.
Von Willebrand Disease (vWD) is due to an inherited deficiency in von Willebrand Factor (vWF). Which of the following factors are also affected as a result of deficiency of vWF?
Correct Answer
B. Factor VIII
Explanation
Von Willebrand Disease (vWD) is a condition caused by a deficiency in von Willebrand Factor (vWF). This deficiency affects the clotting factor known as Factor VIII. Therefore, as a result of the deficiency of vWF, Factor VIII is also affected.
17.
Which of the following is heparin treatment MOST correlated to?
Correct Answer
F. Antithrombin deficiency
Explanation
Heparin treatment is most correlated to antithrombin deficiency. Heparin is a medication that works by enhancing the activity of antithrombin, a natural anticoagulant in the body. Antithrombin deficiency is a condition where there is a decreased level or impaired function of antithrombin, leading to an increased risk of blood clot formation. Heparin is commonly used to prevent or treat blood clots in individuals with antithrombin deficiency.
18.
Calcium is the trivial name for which of the following factors?
Correct Answer
D. Factor IV
Explanation
Calcium is the trivial name for Factor IV.
19.
Which of the following inactivates the extrinsic pathway?
Correct Answer
A. Lipoprotein associated coagulation inhibitor
Explanation
The extrinsic pathway is a part of the blood clotting process. Lipoprotein associated coagulation inhibitor is a protein that inhibits the activity of the extrinsic pathway. It prevents the formation of blood clots by blocking the activation of factor X, which is a key step in the extrinsic pathway. Therefore, lipoprotein associated coagulation inhibitor inactivates the extrinsic pathway.
20.
Which of the following works with thrombin in aiding the degradation of clotting factors?
Correct Answer
D. All of the above
Explanation
Thrombin plays a crucial role in the clotting process, but it also needs assistance in breaking down clotting factors to prevent excessive clot formation. Thrombomodulin is a protein that binds to thrombin and activates protein C. Activated protein C, in turn, helps degrade clotting factors. Protein S works in conjunction with protein C to enhance its anticoagulant activity. Therefore, all of the above options (thrombomodulin, protein C, and protein S) work together with thrombin to aid in the degradation of clotting factors.
21.
Which of the following is PRIMARILY responsible for formation of fibrin polymers?
Correct Answer
A. Factor VIIIa
Explanation
Factor VIIIa is primarily responsible for the formation of fibrin polymers. Factor VIIIa is a cofactor that works together with Factor IXa to activate Factor Xa, which then converts prothrombin to thrombin. Thrombin then acts on fibrinogen, converting it into fibrin monomers. These fibrin monomers then polymerize to form fibrin polymers, which are the main component of blood clots. Therefore, Factor VIIIa plays a crucial role in the formation of fibrin polymers.
22.
Which of the following is NOT calcium dependent?
Correct Answer
B. Factor III
Explanation
Factor III, also known as tissue factor, is not calcium dependent. Tissue factor is a protein that plays a crucial role in initiating the coagulation cascade. Unlike other clotting factors, it does not require calcium ions for its activity. Calcium ions are essential for the activation of other clotting factors such as Factor II, VII, IX, and X. Therefore, Factor III is the correct answer as it is the only factor in the given options that is not calcium dependent.
23.
Which of the following is NOT found in the prothrombinase complex?
Correct Answer
E. Factor VIIIa
Explanation
Factor VIIIa is not found in the prothrombinase complex. The prothrombinase complex is a complex of enzymes and cofactors that converts prothrombin to thrombin during the coagulation cascade. It consists of factor Xa, factor Va, calcium ions, and phospholipids. Factor VIIIa, on the other hand, is not directly involved in the prothrombinase complex but plays a role in the intrinsic pathway of coagulation.
24.
Prothrombin is cleaved to form a 2-chain active thrombin molecule, a serine protease, that will cleave fibrinogen to form fibrin. The short chain of the active thrombin molecule is the ____ chain.
Correct Answer
A. A
Explanation
The short chain of the active thrombin molecule is the A chain.
25.
Thrombin combines with _________ present on endothelial cell surfaces forming a complex that converts protein C to protein Ca.
Correct Answer
C. Thrombomodulin
Explanation
Thrombin combines with thrombomodulin present on endothelial cell surfaces forming a complex that converts protein C to protein Ca. Thrombomodulin is a glycoprotein that is expressed on the surface of endothelial cells. When thrombin binds to thrombomodulin, it changes its substrate specificity and instead of promoting clot formation, it activates protein C. Activated protein C then inhibits factors Va and VIIIa, which are necessary for the formation of blood clots, thereby preventing excessive clotting and maintaining blood flow.
26.
Which of the following is characterized by easy bruising and prolonged bleeding?
Correct Answer
A. HemopHilia A
Explanation
Hemophilia A is characterized by easy bruising and prolonged bleeding. This is because it is a genetic disorder that affects the blood's ability to clot properly. It is caused by a deficiency in clotting factor VIII, which is necessary for the formation of blood clots. Without enough factor VIII, the blood cannot clot effectively, leading to excessive bleeding and easy bruising.
27.
Which of the following involves the transglutaminase reaction?
Correct Answer
B. Factor XIII
Explanation
Factor XIII is the correct answer because it is the only factor listed that involves the transglutaminase reaction. Transglutaminase is an enzyme that cross-links proteins by forming covalent bonds between glutamine and lysine residues. Factor XIII is a blood clotting factor that plays a crucial role in stabilizing blood clots by cross-linking fibrin strands, which is achieved through the transglutaminase activity of Factor XIII.
28.
Which of the following is characterized by prolonged coagulation time?
Correct Answer
B. HemopHilia B
Explanation
Hemophilia B is characterized by prolonged coagulation time. Hemophilia B is a genetic disorder caused by a deficiency or dysfunction of clotting factor IX. This deficiency leads to impaired blood clotting and prolonged bleeding time.
29.
Which of the following is also seen in women on oral contraceptives?
Correct Answer
C. Disorders of Fibrinogen and Factor XIII
Explanation
Women on oral contraceptives may also experience disorders of fibrinogen and factor XIII. Oral contraceptives can affect the levels of various coagulation factors in the blood, including fibrinogen and factor XIII. Fibrinogen is a protein necessary for blood clot formation, and factor XIII is an enzyme that stabilizes the clot. Changes in the levels or function of these factors can lead to abnormal clotting or bleeding. Therefore, women on oral contraceptives may be at an increased risk of developing disorders related to fibrinogen and factor XIII.
30.
Which of the following is the most commonly inherited bleeding disorder in humans?
Correct Answer
D. Von Willebrand Disease
Explanation
Von Willebrand Disease is the most commonly inherited bleeding disorder in humans. It is caused by a deficiency or dysfunction of von Willebrand factor (VWF), a protein that plays a crucial role in blood clotting. This disorder can result in prolonged bleeding, easy bruising, and other symptoms related to abnormal clotting. Hemophilia A and B are also inherited bleeding disorders, but they are less common than Von Willebrand Disease. Disorders of Fibrinogen and Factor XIII, Factor XI and Contact Activation, and Antithrombin deficiency are less commonly inherited bleeding disorders.
31.
Which of the following is common in Ashkenazic Jews?
Correct Answer
E. Factor XI and Contact Activation
Explanation
Factor XI and Contact Activation are common in Ashkenazic Jews. This is because Ashkenazic Jews have a higher prevalence of certain genetic mutations that lead to factor XI deficiency, a clotting disorder. Contact activation is a process that triggers blood clotting, and factor XI is involved in this process. Therefore, Ashkenazic Jews are more likely to have abnormalities in factor XI and contact activation, leading to an increased risk of bleeding disorders.
32.
Which of the following inhibits thrombin as well as Factors IXa, Xa, XIa, and XIIa?
Correct Answer
A. Antithrombin III
Explanation
Antithrombin III is the correct answer because it is a natural anticoagulant that inhibits the activity of several clotting factors, including thrombin, Factors IXa, Xa, XIa, and XIIa. It works by binding to these factors and preventing their interaction with other molecules involved in the clotting cascade. This inhibition helps regulate and prevent excessive blood clotting, reducing the risk of thrombosis. Heparin, another option listed, also inhibits these clotting factors but primarily works by enhancing the activity of antithrombin III. Thrombomodulin and calcium do not directly inhibit these clotting factors.
33.
Vitamin ___ is responsible for the ___________ of coagulation factors.
Correct Answer
C. K, carboxylation
Explanation
Vitamin K is responsible for the carboxylation of coagulation factors. Carboxylation is a process that adds a carboxyl group to a molecule. In the context of coagulation factors, carboxylation is important for their activation and function in blood clotting. Therefore, the correct answer is K, carboxylation.
34.
Warfarin is a common anticoagulant. What is its mode of action?
Correct Answer
A. Competitive inhibition of Vitamin K
Explanation
Warfarin works by competitively inhibiting the action of vitamin K, which is necessary for the production of clotting factors in the body. By blocking the action of vitamin K, warfarin reduces the production of clotting factors and slows down the clotting process. This helps to prevent the formation of blood clots and is why warfarin is commonly used as an anticoagulant.
35.
Rodenticides employ coumarin-type drugs such as warfarin to induce death by internal hemorrhaging. Which of the following enzymes are inhibited by these drugs?
Correct Answer
C. Epoxide reductase
Explanation
Warfarin, a coumarin-type drug, inhibits the enzyme epoxide reductase. Epoxide reductase is responsible for converting vitamin K epoxide back to its active form, vitamin K hydroquinone. By inhibiting this enzyme, warfarin prevents the recycling of vitamin K and ultimately disrupts the production of clotting factors in the liver. This leads to a decrease in blood clotting ability and can result in internal hemorrhaging, ultimately causing death.
36.
The prothrombin time test is used to measure clotting factors found in which pathway besides the common pathway?
Correct Answer
B. Extrinsic
Explanation
The prothrombin time test measures clotting factors in the extrinsic pathway. This pathway is activated when tissue factor is released from damaged blood vessels, leading to the production of thrombin and ultimately the formation of a blood clot. The test is commonly used to monitor the effectiveness of anticoagulant medications and to diagnose clotting disorders.
37.
The activated partial thromboplastin time test is used to measure clotting factors found in which pathway besides the common pathway?
Correct Answer
A. Intrinsic
Explanation
The activated partial thromboplastin time (aPTT) test is used to measure clotting factors in the intrinsic pathway of the coagulation cascade. This pathway is responsible for initiating clot formation within blood vessels. The aPTT test helps evaluate the function of factors such as VIII, IX, XI, and XII, which are involved in this pathway. The test is commonly used to monitor the effectiveness of anticoagulant therapy, diagnose bleeding disorders, and assess the risk of excessive bleeding during surgical procedures.