Block 2 Pace Quiz Sem 1 Biochem

1. Which of the following substances, produced by platelets, is responsible for the activation of platelets?

Serotonin

Phosphatidyl inositol

Thromboxane

Prostaglandins

Leukotrienes

Thromboxane is a substance produced by platelets that is responsible for the activation of platelets. It plays a crucial role in the formation of blood clots by promoting platelet aggregation and vasoconstriction.

Explanation

Thromboxane is a substance produced by platelets that is responsible for the activation of platelets. It plays a crucial role in the formation of blood clots by promoting platelet aggregation and vasoconstriction.

2. A 2-year-old boy has a bleeding disorder that is clinically indistinguishable from classical hemophilia (hemophilia A). However, tests for factor VIII activity show a normal protein with normal biological properties. Which of the following observations would suggest that the boy has hemophilia B?

The plasma level of von Willebrand factor is reduced to 10% of normal

Injected heparin has a paradoxical pro-coagulant effect

The amino acid hydrolyxate of a plasma sample contains an abnormally large quantity of y-carboxyglutamate

The prothrombin time is normal, but the activated partial thromboplastin time is greatly reduced

If the boy's blood clots when mixed with the blood of a patient with hemophilia A, but not when mixed with blood from a patient with hemophilia B, it suggests that the boy has hemophilia B. This is because hemophilia A is caused by a deficiency in factor VIII, while hemophilia B is caused by a deficiency in factor IX. Since the boy's blood does not clot when mixed with blood from a patient with hemophilia B, it indicates that the boy's bleeding disorder is not due to a deficiency in factor IX, confirming that he has hemophilia B.

Explanation

If the boy's blood clots when mixed with the blood of a patient with hemophilia A, but not when mixed with blood from a patient with hemophilia B, it suggests that the boy has hemophilia B. This is because hemophilia A is caused by a deficiency in factor VIII, while hemophilia B is caused by a deficiency in factor IX. Since the boy's blood does not clot when mixed with blood from a patient with hemophilia B, it indicates that the boy's bleeding disorder is not due to a deficiency in factor IX, confirming that he has hemophilia B.

3. 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?

Factor VII

Factor VIII

Factor IX

Factor X

Factor Xa

Von Willebrand Disease (vWD) is caused by a deficiency in von Willebrand Factor (vWF). Factor VIII is also affected as a result of this deficiency. Von Willebrand Factor plays a crucial role in stabilizing and protecting Factor VIII in the blood. Therefore, a deficiency in vWF leads to a decrease in the levels and function of Factor VIII, which is necessary for blood clotting.

Explanation

Von Willebrand Disease (vWD) is caused by a deficiency in von Willebrand Factor (vWF). Factor VIII is also affected as a result of this deficiency. Von Willebrand Factor plays a crucial role in stabilizing and protecting Factor VIII in the blood. Therefore, a deficiency in vWF leads to a decrease in the levels and function of Factor VIII, which is necessary for blood clotting.

4. Patients with vitamin K deficiency are most likely to have prolonged coagulation time because of problems associated with :

Factor V

Factor VIII

Factor II

High molecular weight kin inogen

Von Willebrand factor

Patients with vitamin K deficiency are most likely to have prolonged coagulation time because vitamin K is essential for the synthesis of coagulation factors, including factor II (also known as prothrombin). Without sufficient vitamin K, the liver cannot produce enough factor II, leading to impaired blood clotting and prolonged coagulation time.

Explanation

Patients with vitamin K deficiency are most likely to have prolonged coagulation time because vitamin K is essential for the synthesis of coagulation factors, including factor II (also known as prothrombin). Without sufficient vitamin K, the liver cannot produce enough factor II, leading to impaired blood clotting and prolonged coagulation time.

5. A mother finds her 4-year-old daughter with a bag of rat poison . The child has already eaten almost the whole amount in the bag. It turns out that the active ingredient of the rat poison is warfarin. On seeing this child in the emergency room one hour later, what should you do?

Tell the mother that the child is going to die in a few hours

Inject a high dose of tissue-type plasminogen activator, then keep monitoring the prothrombin time over the next days

Make an excha ng-e transfusion immedlately, then keep monitoring the activated partial thromboplastin time over the next days

Transfuse fresh frozen plasma Immediately, to replace the defective clotting factors

In this scenario, the correct course of action is to perform gastric lavage to remove any remaining poison from the child's stomach and then administer a high dose of vitamin K. Warfarin is an anticoagulant that inhibits the production of clotting factors in the body, which can lead to excessive bleeding. Vitamin K is essential for the production of these clotting factors, so administering a high dose can help counteract the effects of the rat poison. Monitoring the prothrombin time over the next few days is necessary to assess the effectiveness of the treatment and ensure that the child's blood is clotting properly.

Explanation

In this scenario, the correct course of action is to perform gastric lavage to remove any remaining poison from the child's stomach and then administer a high dose of vitamin K. Warfarin is an anticoagulant that inhibits the production of clotting factors in the body, which can lead to excessive bleeding. Vitamin K is essential for the production of these clotting factors, so administering a high dose can help counteract the effects of the rat poison. Monitoring the prothrombin time over the next few days is necessary to assess the effectiveness of the treatment and ensure that the child's blood is clotting properly.

6. Which of the following works with thrombin in aiding the degradation of clotting factors?

Thrombomodulin

Protein C

Protein S

All of the above

None of the above

Thrombin is a key enzyme involved in the clotting process. Thrombomodulin is a protein that binds to thrombin and alters its activity. When thrombin binds to thrombomodulin, it loses its ability to promote clotting and instead activates protein C. Protein C, in the presence of protein S, acts as an anticoagulant by degrading clotting factors Va and VIIIa, which are necessary for the clotting process to occur. Therefore, all of the above options (thrombomodulin, protein C, and protein S) work together with thrombin in aiding the degradation of clotting factors.

Explanation

Thrombin is a key enzyme involved in the clotting process. Thrombomodulin is a protein that binds to thrombin and alters its activity. When thrombin binds to thrombomodulin, it loses its ability to promote clotting and instead activates protein C. Protein C, in the presence of protein S, acts as an anticoagulant by degrading clotting factors Va and VIIIa, which are necessary for the clotting process to occur. Therefore, all of the above options (thrombomodulin, protein C, and protein S) work together with thrombin in aiding the degradation of clotting factors.

7. Plate let adhesion, the process of platelets binding to exposed subendothelial tissue after vascular injury, is primarily mediated by?

Endothelial cells

Subendothelial cells

Platelets

Clotting factors

Von Willebrand Factor

Platelet adhesion is the process of platelets binding to exposed subendothelial tissue after vascular injury. This process is primarily mediated by Von Willebrand Factor. Von Willebrand Factor is a protein that is released from endothelial cells and binds to platelets, allowing them to adhere to the damaged blood vessel walls. This protein plays a crucial role in the initial stages of blood clot formation and is essential for hemostasis.

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. Von Willebrand Factor is a protein that is released from endothelial cells and binds to platelets, allowing them to adhere to the damaged blood vessel walls. This protein plays a crucial role in the initial stages of blood clot formation and is essential for hemostasis.

8. Antithrombin III is a circulating protease inhibitor that becomes active in the presence of :

Thromboplastin

Thrombomodulin

Heparin

Vitamin K

Urokinase

Antithrombin III is a circulating protease inhibitor that becomes active in the presence of heparin. Heparin enhances the inhibitory activity of antithrombin III by binding to it and accelerating the inhibition of clotting factors, particularly thrombin. This interaction between heparin and antithrombin III is crucial in preventing the formation of blood clots. Therefore, the correct answer is heparin.

Explanation

Antithrombin III is a circulating protease inhibitor that becomes active in the presence of heparin. Heparin enhances the inhibitory activity of antithrombin III by binding to it and accelerating the inhibition of clotting factors, particularly thrombin. This interaction between heparin and antithrombin III is crucial in preventing the formation of blood clots. Therefore, the correct answer is heparin.

9. Which vasopermeability factor is secreted by activated platelets?

Bradykinin

Histamine

Thrombin

Thromboxane

Serotonin

Serotonin is the correct answer because it is a vasopermeability factor that is secreted by activated platelets. Serotonin plays a role in increasing vascular permeability, which allows fluids and cells to move from blood vessels into tissues. This process is important for inflammation and wound healing. Serotonin is released by platelets during activation and contributes to the inflammatory response by promoting vasodilation and increased vascular permeability.

Explanation

Serotonin is the correct answer because it is a vasopermeability factor that is secreted by activated platelets. Serotonin plays a role in increasing vascular permeability, which allows fluids and cells to move from blood vessels into tissues. This process is important for inflammation and wound healing. Serotonin is released by platelets during activation and contributes to the inflammatory response by promoting vasodilation and increased vascular permeability.