BLOOD 2
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Questions and Answers

Where are platelets formed in the body?

  • Spleen
  • Liver
  • Lungs
  • Bone marrow (correct)

    • What is the normal concentration of platelets in the blood?

  • 50,000 - 150,000/ μL
  • 650,000 - 850,000/ μL
  • 450,000 - 650,000/ μL
  • 150,000 - 450,000/ μL (correct)

    • What is the half-life of platelets in the blood?

  • 8 to 12 days (correct)
  • 15 to 20 days
  • 3 to 5 days
  • More than 20 days

    • Which organelle is NOT found within platelets?

    <p>Nucleus</p> Signup and view all the answers

    What is the main function of the coat of glycoproteins on platelets' membrane?

    <p>Repulses adherence to injured areas of the vessel wall</p> Signup and view all the answers

    Which enzyme system is NOT found within platelets?

    <p>ATP synthase</p> Signup and view all the answers

    What is the function of serum in blood clotting?

    <p>It is blood plasma minus its fibrinogen and most of the other clotting factors</p> Signup and view all the answers

    What is the role of activated platelets in blood clot contraction?

    <p>Activating platelet thrombosthenin, actin, and myosin molecules</p> Signup and view all the answers

    Which factor is responsible for catalyzing the cross-linkage in blood clotting?

    <p>Factor XIII (fibrin-stabilizing factor)</p> Signup and view all the answers

    What is the rate-limiting factor in causing blood coagulation?

    <p>Formation of prothrombin activator</p> Signup and view all the answers

    Which pathway has fewer steps and occurs rapidly in blood coagulation?

    <p>Extrinsic pathway</p> Signup and view all the answers

    Where does the intrinsic pathway for blood coagulation begin?

    <p>Within the blood itself</p> Signup and view all the answers

    What is the role of vitamin K in blood clotting?

    <p>Is required by the liver for normal activation of prothrombin</p> Signup and view all the answers

    Which enzyme acts on fibrinogen to form fibrin in blood coagulation?

    <p>Thrombin</p> Signup and view all the answers

    What is the function of fibrin-stabilizing factor in blood clotting?

    <p>(I) Activated XIII Loose fibrin threads STRENGTHENED FIBRIN THREADS 3</p> Signup and view all the answers

    Why does little fibrinogen normally leak from the blood vessels into the interstitial fluids?

    <p>Because of its large molecular size</p> Signup and view all the answers

    How do the intrinsic and extrinsic mechanisms usually operate when a blood vessel ruptures during tissue injury?

    <p>The extrinsic mechanism stops blood in the injured vessel while the intrinsic mechanism clots blood that escaped into the tissue before the vessel was sealed off.</p> Signup and view all the answers

    What limits the explosive nature of the extrinsic pathway in blood coagulation?

    <p>The amount of tissue factor released from traumatized tissues and by the quantities of Factors X, VII, and V in the blood.</p> Signup and view all the answers

    What is the main factor responsible for the prevention of blood coagulation while it is circulating in the blood vessels?

    <p>The smoothness of the endothelial cell surface</p> Signup and view all the answers

    What happens when the endothelial wall is damaged?

    <p>Factor XII and platelets are activated, setting off the intrinsic pathway of clotting</p> Signup and view all the answers

    Which substance is among the most important anticoagulants in the blood, responsible for removing thrombin?

    <p>Fibrin fibers formed during the process of clotting</p> Signup and view all the answers

    What is the main function of Heparin in the blood?

    <p>Prevents contact activation of platelets and Factor XII</p> Signup and view all the answers

    What can cause thromboembolism according to the text?

    <p>Release of tissue thromboplastin into the blood from traumatized tissue</p> Signup and view all the answers

    What are the causes of thromboembolic conditions mentioned in the text?

    <p>Roughened vessel surfaces associated with atherosclerosis</p> Signup and view all the answers

    What is a characteristic feature of DIC (Disseminated Intravascular Coagulation)?

    <p>Bleeding due to removal of clotting factors by widespread clotting</p> Signup and view all the answers

    'Thromboembolic' conditions generally refer to:

    <p>Conditions involving widespread clotting and embolism formation</p> Signup and view all the answers

    What does antithrombin III mainly combine with in order to prevent clot formation?

    <p>Thrombin adsorbed to fibrin fibers</p> Signup and view all the answers

    What happens when a vessel is ruptured according to Slide 40?

    <p>Procoagulants from area of tissue damage become activated, overriding anticoagulants</p> Signup and view all the answers

    What is responsible for inhibiting platelet aggregation and initiation of blood clotting, according to Slide 40?

    <p>Intact endothelial cells producing prostacyclin and nitric oxide (NO)</p> Signup and view all the answers

    What is the role of aspirin in hemostasis?

    <p>Inhibiting the formation of a platelet plug</p> Signup and view all the answers

    What prevents further blood loss by adhering to damaged surfaces of blood vessels?

    <p>Fibrin fibers</p> Signup and view all the answers

    Which event results from a series of chemical reactions and culminates in the formation of fibrin threads?

    <p>Blood clotting (coagulation)</p> Signup and view all the answers

    What is the first event in hemostasis?

    <p>Vascular constriction</p> Signup and view all the answers

    What is the primary function of the aggregated platelet plug in hemostasis?

    <p>Physically sealing the break in the vessel</p> Signup and view all the answers

    What role does von Willebrand factor (vWF) play in platelet plug formation?

    <p>Adhesion of platelets to the subendothelial matrix</p> Signup and view all the answers

    What is the significance of thromboxane A2 in platelet plug formation?

    <p>Inducing profound vasoconstriction</p> Signup and view all the answers

    How does aspirin work to prevent blood loss?

    <p>By irreversibly inhibiting the enzyme cyclooxygenase (COX-1)</p> Signup and view all the answers

    What is the primary function of hemostasis?

    <p>Prevention of blood loss</p> Signup and view all the answers

    What is the role of tissue factor in the extrinsic pathway of blood clotting?

    <p>Formation of prothrombin activator</p> Signup and view all the answers

    What is the function of activated factor X in the intrinsic pathway of blood coagulation?

    <p>Activates factor IX</p> Signup and view all the answers

    What is the primary deficiency in hemophilia A?

    <p>Factor VIII</p> Signup and view all the answers

    What is the role of thrombin in blood coagulation?

    <p>Converts fibrinogen into fibrin</p> Signup and view all the answers

    Why do we use Ethylenediaminetetraacetic acid (EDTA) tube to collect blood for CBC?

    <p>Chelates calcium ions required for blood clotting</p> Signup and view all the answers

    What is the final step before dissolution of a blood clot?

    <p>Release of tissue plasminogen activator</p> Signup and view all the answers

    What is the main function of fibrous organization in hemostasis?

    <p>Repair the injured vessel wall</p> Signup and view all the answers

    Which pathway requires the activation of factor XII and release of platelet phospholipids?

    <p>(b) Intrinsic pathway</p> Signup and view all the answers

    What role does activated factor V play in blood clotting?

    <p>Formation of prothrombin activator</p> Signup and view all the answers

    What is the significance of hemophilia A and hemophilia B being X-linked disorders?

    <p>They predominantly affect males.</p> Signup and view all the answers

    What is the primary role of plasmin in blood coagulation?

    <p>Dissolution of remaining unnecessary blood clots</p> Signup and view all the answers

    What is the main function of thrombosthenin in platelets?

    <p>ATP production</p> Signup and view all the answers

    Which organelle is NOT found within platelets?

    <p>Nucleus</p> Signup and view all the answers

    What is the normal concentration of platelets in the blood?

    <p>200,000 - 450,000/ μL</p> Signup and view all the answers

    What is the main role of the coat of glycoproteins on platelet membranes?

    <p>Repulse adherence to injured areas of the vessel wall</p> Signup and view all the answers

    What is responsible for inhibiting platelet aggregation and initiation of blood clotting, according to the text?

    <p>Vascular endothelial cells</p> Signup and view all the answers

    What limits the explosive nature of the extrinsic pathway in blood coagulation?

    <p>Factor VII</p> Signup and view all the answers

    What is the primary role of thromboxane A2 in platelet plug formation?

    <p>Activating platelet aggregation</p> Signup and view all the answers

    What is the primary function of Heparin in the blood?

    <p>Inhibiting blood coagulation</p> Signup and view all the answers

    What is the significance of hemophilia A and hemophilia B being X-linked disorders?

    <p>They are more common in males than in females</p> Signup and view all the answers

    What happens when the endothelial wall is damaged?

    <p>von Willebrand factor adheres to the exposed collagen</p> Signup and view all the answers

    What is the main factor responsible for the prevention of blood coagulation while it is circulating in the blood vessels?

    <p>Antithrombin III in plasma</p> Signup and view all the answers

    What is the role of tissue factor in the extrinsic pathway of blood clotting?

    <p>Initiating blood coagulation cascade</p> Signup and view all the answers

    What is responsible for inhibiting platelet aggregation and initiation of blood clotting, according to Slide 40?

    <p>Aspirin</p> Signup and view all the answers

    What is the function of activated factor X in the intrinsic pathway of blood coagulation?

    <p>Catalyzing conversion of prothrombin to thrombin</p> Signup and view all the answers

    'Thromboembolic' conditions generally refer to:

    <p>'Blockage of a blood vessel'</p> Signup and view all the answers

    Why do we use Ethylenediaminetetraacetic acid (EDTA) tube to collect blood for CBC?

    <p>To prevent coagulation of blood during storage and transportation</p> Signup and view all the answers

    What is the primary function of fibrous organization in hemostasis?

    <p>Preventing further blood loss by adhering to damaged surfaces of blood vessels</p> Signup and view all the answers

    What role does activated factor V play in blood clotting?

    <p>Accelerating the formation of fibrin fibers</p> Signup and view all the answers

    Which of the following statements about blood coagulation is true?

    <p>The extrinsic pathway requires damaged platelets to initiate the formation of prothrombinase</p> Signup and view all the answers

    What is the role of thrombin in blood coagulation?

    <p>Thrombin strengthens the fibrin meshwork by forming covalent bonds between fibrin monomer molecules</p> Signup and view all the answers

    What is the primary function of hemostasis?

    <p>To stop bleeding and maintain blood within a damaged blood vessel</p> Signup and view all the answers

    What is the main function of the aggregated platelet plug in hemostasis?

    <p>To adhere to damaged surfaces of blood vessels and prevent further blood loss</p> Signup and view all the answers

    What is responsible for inhibiting platelet aggregation and initiation of blood clotting, according to Slide 40?

    <p>Antithrombin III</p> Signup and view all the answers

    Why does little fibrinogen normally leak from the blood vessels into the interstitial fluids?

    <p>Because fibrinogen is formed in the liver and remains primarily in the plasma</p> Signup and view all the answers

    What is the significance of thromboxane A2 in platelet plug formation?

    <p>It promotes platelet aggregation and vasoconstriction at the site of injury</p> Signup and view all the answers

    What can cause thromboembolism according to the text?

    <p>Increased permeability of capillaries during pathological conditions</p> Signup and view all the answers

    What is responsible for removing thrombin from the clot, thus preventing further clot growth?

    <p>Plasmin</p> Signup and view all the answers

    How does Ethylenediaminetetraacetic acid (EDTA) work in collecting blood for CBC?

    <p>It chelates calcium ions necessary for blood coagulation</p> Signup and view all the answers

    What is the primary function of Heparin in the blood?

    <p>To prevent further clot growth by inhibiting thrombin activity</p> Signup and view all the answers

    What is the role of thrombomodulin in blood coagulation?

    <p>Binds with thrombin and activates plasma protein C</p> Signup and view all the answers

    What can cause thromboembolism according to the text?

    <p>Roughened vessel surfaces associated with atherosclerosis</p> Signup and view all the answers

    What is the primary function of heparin in blood coagulation?

    <p>Inhibits thrombin and activated factors X, XI, IX, and XII</p> Signup and view all the answers

    What is the main function of the coat of glycocalyx on the endothelial cell surface?

    <p>Inhibits platelet aggregation and initiation of blood clotting</p> Signup and view all the answers

    What is the primary role of antithrombin III in preventing clot formation?

    <p>Inhibits activated factors V and VIII</p> Signup and view all the answers

    Where do platelets originate in the body?

    <p>Bone marrow</p> Signup and view all the answers

    What is the function of soluble oxalate and citrate ion outside the body?

    <p>Decreases ionic calcium level to block blood coagulation</p> Signup and view all the answers

    What is the significance of thromboxane A2 in platelet plug formation?

    <p>Inhibits platelet aggregation and initiation of blood clotting depending on slide 40</p> Signup and view all the answers

    What is responsible for inhibiting platelet aggregation and initiation of blood clotting, according to Slide 40?

    <p>A layer of glycocalyx on the endothelium</p> Signup and view all the answers

    What is the main factor responsible for preventing blood coagulation while it is circulating in the blood vessels?

    <p>A layer of glycocalyx on the endothelium</p> Signup and view all the answers

    Which pathway requires activation of factor XII and release of platelet phospholipids?

    <p>Intrinsic pathway</p> Signup and view all the answers

    What is the primary role of thrombin in blood coagulation?

    <p>Converting fibrinogen into fibrin</p> Signup and view all the answers

    What is the main function of fibrous organization in hemostasis?

    <p>Forming connective tissue all through the clot</p> Signup and view all the answers

    Which substance is among the most important anticoagulants in the blood, responsible for removing thrombin?

    <p>Plasmin</p> Signup and view all the answers

    What does 'Thromboembolic' conditions generally refer to?

    <p>Blood clots that obstruct blood vessels</p> Signup and view all the answers

    What is the main function of the aggregated platelet plug in hemostasis?

    <p>Stopping bleeding until the vessel can be repaired</p> Signup and view all the answers

    What is responsible for inhibiting platelet aggregation and initiation of blood clotting, according to the text?

    <p>Heparin</p> Signup and view all the answers

    What is the role of tissue factor in the extrinsic pathway of blood clotting?

    <p>Formation of prothrombin activator</p> Signup and view all the answers

    What is the first event in hemostasis?

    <p>Vascular constriction</p> Signup and view all the answers

    What is the function of activated factor X in the intrinsic pathway of blood coagulation?

    <p>Combining with tissue phospholipids to form prothrombin activator</p> Signup and view all the answers

    What is responsible for inhibiting platelet aggregation and initiation of blood clotting, according to Slide 40?

    <p>Antithrombin III</p> Signup and view all the answers

    What limits the explosive nature of the extrinsic pathway in blood coagulation?

    <p>Blood trauma</p> Signup and view all the answers

    Platelets have a half-life in the blood of 5 to 7 days.

    <p>False</p> Signup and view all the answers

    Platelets contain nuclei.

    <p>False</p> Signup and view all the answers

    Platelets contain enzyme systems that synthesize insulin.

    <p>False</p> Signup and view all the answers

    The coat of glycoproteins on platelet membranes causes adherence to normal endothelium only.

    <p>False</p> Signup and view all the answers

    Platelets are eliminated from the circulation mainly by the liver.

    <p>False</p> Signup and view all the answers

    Platelets contain large amounts of phospholipids that inhibit multiple stages in the blood-clotting process.

    <p>False</p> Signup and view all the answers

    The edges of the broken blood vessel are pulled together by the retraction of the clot, contributing further to hemostasis.

    <p>True</p> Signup and view all the answers

    Serum is blood plasma minus its fibrinogen and most of the other clotting factors.

    <p>True</p> Signup and view all the answers

    Platelets contribute directly to clot contraction by activating platelet thrombosthenin, actin, and myosin molecules.

    <p>True</p> Signup and view all the answers

    Most of the proteins involved in blood-clotting are inactive forms of proteolytic enzymes.

    <p>True</p> Signup and view all the answers

    Prothrombin activator is usually considered to be the rate-limiting factor in causing blood coagulation.

    <p>True</p> Signup and view all the answers

    Fibrin-stabilizing factor, also known as factor XIII, catalyzes the cross-linkage of fibrin to form a stable clot.

    <p>True</p> Signup and view all the answers

    The intrinsic and extrinsic mechanisms usually operate simultaneously in response to tissue injury.

    <p>True</p> Signup and view all the answers

    Clots are typically fully formed in 3 to 6 minutes.

    <p>True</p> Signup and view all the answers

    The extrinsic pathway for blood coagulation requires fewer steps than the intrinsic pathway and occurs rapidly.

    <p>True</p> Signup and view all the answers

    Thrombin is an enzyme with weak proteolytic capabilities and acts on fibrinogen to form fibrin monomer.

    <p>True</p> Signup and view all the answers

    Fibrin monomer has the automatic capability to polymerize with other fibrin monomer molecules to form fibrin fibers.

    <p>True</p> Signup and view all the answers

    Fibrinogen, a high-molecular-weight protein found in plasma, does not normally leak from blood vessels into interstitial fluids due to its large molecular size.

    <p>True</p> Signup and view all the answers

    Blood clotting depends on the balance between procoagulants and anticoagulants.

    <p>True</p> Signup and view all the answers

    Prostacyclin and nitric oxide (NO) promote platelet aggregation and initiation of blood clotting.

    <p>False</p> Signup and view all the answers

    Heparin is normally found at a high concentration in the blood.

    <p>False</p> Signup and view all the answers

    Siliconized containers prevent contact activation of platelets and Factor XII.

    <p>True</p> Signup and view all the answers

    Thrombus refers to freely flowing clots in the blood vessels.

    <p>False</p> Signup and view all the answers

    Roughened endothelial surfaces of blood vessels are unlikely to initiate the clotting process.

    <p>False</p> Signup and view all the answers

    DIC (Disseminated Intravascular Coagulation) often results from the presence of large amounts of traumatized tissue releasing tissue factor into the blood.

    <p>True</p> Signup and view all the answers

    T-PA (tissue plasminogen activator) is used when blood must be passed through a heart-lung machine or artificial kidney machine.

    <p>False</p> Signup and view all the answers

    Prothrombin time (PT) measures the integrity of the intrinsic pathway of blood coagulation.

    <p>False</p> Signup and view all the answers

    Activated thromboplastin time (aPTT) measures the integrity of the intrinsic pathway of blood coagulation.

    <p>True</p> Signup and view all the answers

    Activated factor X inhibits thrombin in the intrinsic pathway of blood coagulation.

    <p>False</p> Signup and view all the answers

    Thromboembolic conditions may be triggered by imbalances in the clotting–anticlotting systems.

    <p>True</p> Signup and view all the answers

    The intrinsic pathway is much slower to proceed, usually requiring 1 to 6 minutes to cause clotting.

    <p>True</p> Signup and view all the answers

    Tissue factor is composed especially of phospholipids from the membranes of the tissue plus a lipoprotein complex that functions mainly as a proteolytic enzyme.

    <p>True</p> Signup and view all the answers

    The activated Factor X combines immediately with tissue phospholipids and Factor V to form the complex called prothrombin activator.

    <p>True</p> Signup and view all the answers

    Activated factor V greatly accelerates the protease activity of the prothrombin activator complex.

    <p>True</p> Signup and view all the answers

    The common sites of bleeding in newborns include the central nervous system, and sites of medical interventions such as circumcision, heel sticks, and venipunctures.

    <p>True</p> Signup and view all the answers

    Hemophilia A and B are X-linked disorders that predominantly affect males.

    <p>True</p> Signup and view all the answers

    Patients with more severe hemophilia are less likely to have spontaneous bleeding.

    <p>False</p> Signup and view all the answers

    Thrombin has positive feedback effects: it accelerates the formation of prothrombinase, activates platelets, and acts in a positive-feedback fashion to facilitate its own formation.

    <p>True</p> Signup and view all the answers

    In the absence of calcium ions, blood clotting by either pathway does not occur.

    <p>True</p> Signup and view all the answers

    Fibrous organization or dissolution of the blood clot is an event of hemostasis.

    <p>True</p> Signup and view all the answers

    A clot is meant to be a permanent solution to vessel injury.

    <p>False</p> Signup and view all the answers

    Plasminogen when activated becomes a substance called plasmin (or fibrinolysin) which removes the remaining unnecessary blood clot.

    <p>True</p> Signup and view all the answers

    The formation of a platelet plug is one of the events of hemostasis.

    <p>True</p> Signup and view all the answers

    Thrombocytopenia can lead to increased bleeding time.

    <p>True</p> Signup and view all the answers

    A break must be present in the vessel wall for bleeding to take place from a vessel.

    <p>True</p> Signup and view all the answers

    Platelets do not adhere to the smooth endothelial lining of blood vessels under normal conditions.

    <p>True</p> Signup and view all the answers

    Aspirin works by irreversibly inhibiting the enzyme cyclooxygenase (COX-1) which is required to make the precursors of thromboxane within platelets.

    <p>True</p> Signup and view all the answers

    The clot begins to develop in 15 to 20 seconds if the trauma to the vascular wall is severe.

    <p>False</p> Signup and view all the answers

    The aggregated platelet plug releases several powerful vasodilators that induce profound constriction.

    <p>False</p> Signup and view all the answers

    Clot retraction occurs within a few hours after a clot is formed.

    <p>False</p> Signup and view all the answers

    Platelets begin to contract and usually express most of the fluid from the clot within 20 to 60 minutes.

    <p>True</p> Signup and view all the answers

    Fibrin fibers prevent further blood loss by adhering to damaged surfaces of blood vessels.

    <p>True</p> Signup and view all the answers

    Hemostasis includes fibrous organization or dissolution of the blood clot as one of its events.

    <p>True</p> Signup and view all the answers

    Fibrin threads are formed as a result of a series of chemical reactions culminating in clotting.

    <p>True</p> Signup and view all the answers

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