anticoagulants of blood. An overview. .pptx

What prevents intravascular blood clotting and how clotting can be prevented outside the body. in vitro and in vivo prevention of blood clotting

1. Name blood coagulation tests Platelet Count PC Bleeding Time BT Clotting Time CT Prothrombin Time PT Clotting factor deficient

2. BLOOD COAGULATION TESTS 1. BLEEDING TIME pierce the tip of the finger or earlobe bleeding lasts for 1 to 6 minutes bleeding time is prolonged by Lack of any one of several of the clotting factors Lack of platelets. 2. CLOTTING TIME collect blood in a chemically clean glass test tube tip the tube back and forth about every 30 seconds until the blood has clotted the normal clotting time is 6 to 10 minutes Clotting time is prolonged by Hemophilia DIC (Disseminated Intravascular Coagulation) 3. PROTHROMBIN TIME Blood removed from the patient is immediately oxalated so that none of the prothrombin can change into thrombin. Then, a large excess of calcium ion and tissue factor is quickly mixed with the oxalated blood. The excess calcium nullifies the effect of the oxalate, and the tissue factor activates the prothrombin to thrombin reaction by means of the extrinsic clotting pathway. The time required for coagulation to take place is known as the prothrombin time Normal value 12 seconds Increased in DIC (Disseminated Intravascular Coagulation)

3. Hemophilias Type Cause Deficient factor hemophilia A. classic hemophilia . recessive X-linked genetic disorder results from loss of the small component of Factor VIII . hemophilia B. Christmas disease recessive X-linked genetic disorder Factor IX haemophilia C   autosomal  genetic disorder  not completely recessive factor XI

4. Q. A teenaged boy with numerous nosebleeds was referred to a physician for evaluation prior to a minor surgery. His prothrombin time (PT) was 11 sec (11–15 sec normal), partial thromboplastin time (PTT) was 58 sec (25–40 sec normal), and bleeding time was 6.5 min (2–7 min normal). a) Which pathway of blood coagulation system is most likely abnormal in this young man? b) Draw a flow chart to describe the stages of the affected pathway of blood coagulation system . c) Name an anticoagulant that blocks this pathway of blood coagulation system . 1 + 3+ 1 Key a) intrinsic pathway of blood coagulation system . b) c) heparin

5. Q. A 56 years old lady travelled from Singapore to San Francisco on a non stop 14 hours flight. A few hours after her arrival she experienced sudden shortness of breath and severe central chest pain. She was rushed to the emergency department. On examination she was found to have rapid pulse and fast breathing rate. D dimer test was positive. D-dimer is a fibrin degradation product, a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis. From the history of prolonged sitting in the plane and evidence of intravascular thrombosis from D dimer test, we can infer that intravascular clotting took place in the deep veins of the legs of this patient. a) Enumerate the factors that prevent unwanted blood coagulation in the circulation. b) Name any three drugs used as anticoagulants. c) Which cell produces TPA Tissue Plasminogen Activator? What is the function of TPA? 2+1+2 a) smooth endothelium, streamline flow, anticoagulants (protein C, protein S, antithrombin) b) Heparin, warfarin, aspirin, TPA c) Endothelial cell. TPA cleaves Plasminogen to generate its active form Plasmin which breaks down Fibrin to fibrin degradation product.

6. Q. A clinician is investigating a case of unexplained bleeding episodes due to clotting system abnormality. He advises a number of laboratory tests in order to arrive at a definitive diagnosis. a) Name one lab test that evaluates the extrinsic pathway of blood coagulation and one lab test that evaluates the intrinsic pathway of blood coagulation. b) Name two lab tests that are increased in Haemophilia. c) Name two conditions in which the Platelet count is decreased. 2+ 1.5 + 1.5 a) Prothrombin Time evaluates the extrinsic pathway of blood coagulation Activated Partial Thromboplastin Time evaluates the intrinsic pathway of blood coagulation. b) Activated Partial Thromboplastin Time and Clotting Time c) Idiopathic Thrombocytopenic Purpura and Disseminated Intravascular Coagulation

7. Clinical condition Platelet Count PC Bleeding Time BT Clotting Time CT Prothrombin Time PT Clotting factor deficient Haemophilia Normal Normal Increased Normal VIII (A) IX (B) XI (C) Von willebrand Disease Normal Increased Normal Normal vwf Idiopathic Thrombocytopenic Purpura Decreased Increased Normal Normal None Disseminated Intravascular Coagulation Decreased Increased Increased Increased Decreased

8. Test Haemophilia Von willebrand Disease Idiopathic Thrombocytopenic Purpura Disseminated Intravascular Coagulation Platelet Count PC Normal Normal Decreased Decreased Bleeding Time BT Normal Increased Increased Increased Clotting Time CT Increased Normal Normal Increased Prothrombin Time PT Normal Normal Normal Increased Clotting factor deficient VIII (A) IX (B) XI (C) vwf Platelets All