Hematology & Coagulation Flashcards

Which cell type is responsible for oxygen transport in blood?

Answer: Red blood cells

Red blood cells, or erythrocytes, contain hemoglobin, a protein that binds to oxygen in the lungs and transports it to tissues throughout the body. Their primary function is to deliver oxygen to cells and carry carbon dioxide away as a waste product. This makes them essential for cellular respiration and overall metabolic function, sustaining life.

What is the function of platelets in the blood?

Answer: Assist in clot formation

Platelets, also known as thrombocytes, are small, irregular-shaped cell fragments that play a critical role in hemostasis, the process of stopping bleeding. When a blood vessel is injured, platelets aggregate at the site of injury and form a plug, initiating the coagulation cascade to form a stable blood clot. This prevents excessive blood loss and promotes wound healing.

Which anticoagulant is commonly used for complete blood count (CBC) testing?

Answer: EDTA

Ethylenediaminetetraacetic acid (EDTA) is a common anticoagulant used for complete blood count (CBC) testing. It works by chelating calcium ions, which are essential cofactors for the coagulation cascade, thereby preventing blood from clotting. EDTA preserves cell morphology well, making it ideal for accurate hematological analysis without altering cell structure.

What does a high INR value suggest in coagulation testing?

Answer: Increased bleeding risk

INR (International Normalized Ratio) is a standardized measure of prothrombin time (PT) used to monitor the effectiveness of oral anticoagulant therapy, such as warfarin. A high INR value indicates that the blood is taking longer to clot than normal, suggesting an increased risk of bleeding. Conversely, a low INR suggests a higher risk of clotting, requiring dose adjustment.

Which clotting factor is deficient in Hemophilia A?

Answer: Factor VIII

Hemophilia A is a genetic bleeding disorder caused by a deficiency or defect in clotting Factor VIII. This factor is crucial for the intrinsic pathway of the coagulation cascade, and its absence leads to prolonged bleeding episodes and impaired clot formation. Hemophilia B, in contrast, is due to a Factor IX deficiency, highlighting the specificity of clotting factor disorders.

What condition is characterized by an abnormally high white blood cell count?

Answer: Leukocytosis

Leukocytosis refers to an abnormally high white blood cell (WBC) count in the blood. It is often a sign of infection, inflammation, or other conditions such as leukemia, as the body produces more WBCs to fight off pathogens or respond to stress. This elevated count indicates an active immune response or a disorder of white blood cell production.

Which lab test is used to monitor heparin therapy?

Answer: aPTT

The activated partial thromboplastin time (aPTT) test is used to monitor the effectiveness of unfractionated heparin therapy. Heparin works by enhancing the activity of antithrombin, which inhibits several clotting factors in the intrinsic and common pathways. An elevated aPTT indicates a prolonged clotting time, reflecting the desired anticoagulant effect of heparin and helping to prevent thrombosis.

What is the role of fibrinogen in coagulation?

Answer: Forms fibrin clots

Fibrinogen is a soluble plasma protein that is converted into insoluble fibrin strands by the enzyme thrombin during the final stages of the coagulation cascade. These fibrin strands then polymerize to form a mesh-like network, which traps red blood cells and platelets to create a stable blood clot. This process is essential for hemostasis, effectively stopping bleeding at the site of injury.

Which of the following conditions involves low platelet count?

Answer: Thrombocytopenia

Thrombocytopenia is a medical condition characterized by an abnormally low number of platelets (thrombocytes) in the blood. Platelets are essential for blood clotting, so a reduced count can lead to increased bleeding and bruising. The term itself, derived from Greek, directly translates to 'deficiency of clotting cells'.