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58 Cards in this Set
- Front
- Back
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What is definition of hemorrhage?
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refers to active bleeding into extravascular tissues or spaces resulting from disruption of the integrity of vascular walls.
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Very small "pinpoint" hemorrhage.
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petechiae
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small hemorrhage (<1.0cm)
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purpura
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larger hemorrhage (>1.0cm)
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ecchymoses
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extravascular blood clots are called what?
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hematomas
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blood from the nose
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epistaxis
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coughing of blood from the lungs
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hemoptysis
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vomiting of blood
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hematemesis
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dark, "tarry" blood from stool
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melena
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bright red blood in the stool
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hematochezia
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the clinical significance of hemorrhage depends on three things:
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1. amount
2. location 3. rate of loss |
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Describe the term Hemostasis.
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this refers to the body's intrinsic ability to slow down or stop hemorrhage.
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What is primary Hemostasis?
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The formation of the platelet plug.
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What is secondary hemostasis?
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Coagulation by a variety of factors within the circulatory system. Two pathways are used with the ultimate goal being the formation of fibrin.
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Where are all the factors of the intrinsic pathway?
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within the circulating blood
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Where are all the factors of the extrinsic pathway?
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outside the circulating blood.
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How is the intrinsic pathway activated?
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by the contact of factor XII with the subendothelium.
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What is the intrinsic pathway measured by?
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partial thromboplastin time
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What is the extrinsic pathway measured by?
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prothrombin time.
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What is the common pathway? Define and describe it.
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both the intrinsic and extrinsic pathways converge on inactive factor X to produce active factor X. This converts prothrombin into thrombin. thrombin catalyzes the conversion of fibrinogen into fibrin, which forms a plug.
It is called the common pathway because both the intrinsic and extrinsic pathway lead to this point and go through this pathway. |
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What does antithrombin III do?
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it works in the presence of thrombin and heparin.
It has a negative feedback effect on thrombin. It inactivates Xa and to a lesser extent XIIa, XIa, and IXa. |
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What does prostacyclin do?
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it is from endothelial cells and causes vasodilation and converts ADP into products that inhibit platelet aggregation.
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Describe the thrombomodulin pathway?
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Excess thrombin reacts with undamaged endothelial cells to uncover a membrane receptor (thrombomodulin) which binds and activates circulating Protein C.
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What does activated Protein C do?
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it inhibits further thrombin production by inactivating Va and VIIIa.
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What converts circulating plasminogen into plasmin?
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urokinase and tissue plasminogen activator
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what does plasmin do?
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cleaves fibrinogen and fibrin into fibrin split products which further act to inhibit platelet aggregation, thrombin activity, and cross-linking of fibrin strands.
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What does the D Dimer Test do?
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it is used as an indicator of active fibrinolysis.
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What is thrombosis?
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the production of a thrombus that is inappropriate and life threatening
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What are three predisposing factors to thrombosis. Also called Virchow's Triad.
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1. alteration of vascular endothelium
2. alteration of blood flow 3. alterations of blood components. |
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Describe Arterial thrombi
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these form most frequently in areas of atherosclerotic damage to the vessel wall or, in the heart, over areas of previous myocardial infarction.
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What are Lines of Zahn?
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they are alternating layers of fibrin and aggregated platelets which grossly gives the thrombus a grey, laminated appearance.
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Describe venous thrombi
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these usually form in areas of blood stasis and most clinically significant venous thrombi form in the deep leg veins.
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describe capillary thrombi
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usually due to local endothelial damage. generally consist of platelets and fibrin and are not grossly visible.
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What is thrombolysis?
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Basically, it is the shrinking of the thrombus.
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What is a thromboembolus?
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a fragment or completely detached thrombus from its place of origin. It tumbles through circulation.
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What are the characteristics of a post-mortem blood clot?
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they are a perfect cast of the vessel in which they form, they do not contain lines of Zahn. They are not firmly attached to the vessel wall. They have a "current-jelly" and/or "chicken fat" appearance. They do not break apart easily.
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What is an infarction?
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refers to the process of tissue necrosis secondary to an abrupt reduction in tissue oxygenation.
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What kind of necrosis occurs as a result of anoxia? (except for in the brain)
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coagulation necrosis
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What kind of necrosis occurs in the brain as a result of anoxia?
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liquefactive necrosis
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What is a pale infarct?
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an infarct that leaves the tissue pale-looking because the blood perfusion becomes interrupted.
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What is a red (hemorrhagic) infarct?
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an infarct in tissue that has an alternate blood source. if necrosis occurs, the alternate blood source will bleed into the necrotic tissue.
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Describe DIC (disseminated intravascular coagulation).
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an acquired disorder that is a coagulation abnormality involving the coagulation factors and platelets. It is involved in the microcirulation. Formation of microthrombi.
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Patients with acute DIC are more prone to what?
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hemorrhagic problems
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Patients with chronic DIC have more problems with what?
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thromboses.
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What are the features of DIC in laboratory tests?
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1. decreased platelets.
2. increased bleeding time 3. increased prothrombin time 4. increased aPTT 5. decreased fibrinogen 6. increased fibrin split products |
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What is embolization?
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refers to the process in which a free-floating mass (embolus) is carried through the vascular system to a point distant to its site of origin or entry.
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From where does systemic (arterial) emboli arise?
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80-85% arise from mural thrombi in the left ventricle or left atrial appendage of the heart but valve vegetations, aortic mural thrombi, fragments of atherosclerotic plaque, etc. may also embolize.
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What are the major sites of impaction in an arterial emboli?
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lower extremeties, brain, kidney, and spleen.
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What is the third most common cause of sudden death?
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pulmonary (venous) emboli
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What causes pulmonary (venous) emboli?
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multiple entities that would predispose to venous thrombosis or stasis.
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What is the most significant pathologic change associated with pulmonary emboli?
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pulmonary infarction.
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What kind of necrosis is occuring in a pulmonary embolism?
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hemorrhagic coagulative necrosis
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What are the three things included in the clinical triad of pulmonary embolism?
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1. dyspnea
2. hemoptysis 3. pleuritic chest pain |
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What measurement is done to diagnose a pulmonary embolism?
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serum D-dimer concentrations.
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What is D dimer. Explain why D dimer is used to test for a pulmonary embolism.
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D-dimer is a breakdown product of stabilized (cross linked) fibrin. Elevated serum concentrations imply that the fibrinolytic system has acted on the stabilized fibrin of a preexisting thrombus.
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What is the treatment for a pulmonary embolism?
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patients receive heparin anticoagulation to raise the aPTT.
thrombolytic therapy may also be appropriate long term oral anticoagulation is also recommended |
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What is the most common cause for a fat embolism?
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these occur after long-bone trauma when marrow fat is exposed to the venous circulation.
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What are some clinical outcome that can occur from a fat embolism (2-3 days after the trauma).
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progressive respiratory distress, CNS impairment, and possible renal dysfunction.
These are related to the physical and chemical effects of fat in the circulation. |
