17. The Blood

Platelets: Hemostasis

Open Question
Which of the following does not promote multiple steps in the clotting pathway?a. platelet phospholipids,b. factor XI,c. thrombin,d. Ca²⁺.
Open Question
Multiple ChoiceMore than one choice may apply.A condition resulting from thrombocytopenia isa. thrombus formation.b. embolus formation.c. petechiae.d. hemophilia.
Open Question
___and ____affect almost every aspect of the clotting process. (a) Calcium, vitamin K, (b) Calcium, vitamin B12,(c) Sodium, vitamin K, (d) Sodium, vitamin B12.
Open Question
Multiple ChoiceMore than one choice may apply.Place the letters of these events in the order they occur during hemostasis.a. b. c. d.
Open Question
What is the difference between prothrombin and thrombin?
Open Question
a. Define fibrinolysis.b. What is the importance of this process?
Open Question
What contribution from the intrinsic and the extrinsic pathways is necessary for the common pathway to begin?
Open Question
a. How is clot overgrowth usually prevented?b. List two conditions that may lead to unnecessary (and undesirable) clot formation.
Open Question
a. Define hemostasis.b. List the three major phases of coagulation. Explain what initiates each phase and what the phase accomplishes.c. In what general way do the intrinsic and extrinsic mechanisms of clotting differ?d. Which ion is essential to virtually all stages of coagulation?
Open Question
Why is aspirin sometimes prescribed for the prevention of vascular problems?
Open Question
A test for prothrombin time is used to identify deficiencies in the extrinsic clotting pathway; prothrombin time is prolonged if any of the factors are deficient. A test for activated partial thromboplastin time is used in a similar fashion to detect deficiencies in the intrinsic clotting pathway. Which factor would be deficient if a person had a prolonged prothrombin time but a normal partial thromboplastin time?
Open Question
Almost half of our vitamin K is synthesized by bacteria that inhabit the large intestine. Based on this information, how could taking a broad-spectrum antibiotic for a long time cause frequent nosebleeds?
Open Question
Number the steps of hemostasis in order, putting 1 by the first event, 2 by the second, and so on.

____The intrinsic/contact activation and extrinsic/tissue factor pathways produce factor Xa.
____The clot retracts.
____Thrombin converts fibrinogen to fibrin, and fibrin glues the plug together.
____Platelets are activated, and the platelet plug forms.
____Vasoconstriction and increased tissue pressure decrease blood flow through the vessel.
____Tissue plasminogen activator activates plasmin, which degrades fibrin.
____The common pathway produces thrombin.
Open Question
How do the intrinsic/contact activation and extrinsic/tissue factor coagulation pathways differ? How are they similar?
Open Question
What are the overall goals of the common pathway of coagulation?