Hematology Flashcards
(23 cards)
The anticoagulant of choice for a complete blood count (CBC) is:
EDTA
Which site is responsible for hematopoiesis in an adult?
Axial System
What are the components of plasma?
Water, electrolytes, proteins, nutrients, hormones, waste products
What type of stem cell is responsible for giving rise to all blood cells?
Hematopoietic stem cell
Characteristic of platelets:
They are small, disc-shaped cell fragments that play a crucial role in blood clotting.
The hematocrit test measures the:
Percentage of blood volume occupied by red blood cells
The process of blood cell formation is called:
Hematopoiesis
The two major progenitor cell lines in hematopoiesis are:
Myeloid and lymphoid
What is the primary function of erythropoietin (EPO) in hematopoiesis?
Stimulates RBC production in response to hypoxia
What does the myeloid progenitor cell line give rise to?
The myeloid progenitor cell line produces: Erythrocytes (RBCs): Oxygen transport. Megakaryocytes: Form platelets for clotting. Granulocytes: Includes neutrophils, eosinophils, and basophils for immunity. Monocytes: Develop into macrophages and dendritic cells for phagocytosis and antigen presentation.
Hemoglobin, the protein in red blood cells that carries oxygen, is composed of:
four protein chains (two alpha and two beta) and four heme groups, each containing an iron atom that binds oxygen.
What is the relationship between hemoglobin and hematocrit according to the Rule of 3?
Hematocrit (Hct) ≈ 3 × Hemoglobin (Hb)
Example: If hemoglobin is 12 g/dL, hematocrit is approximately 36%.
A microhematocrit test is performed using:
Capillary tubes (heparinized or non-heparinized). Centrifuge to separate blood components. Microhematocrit reader to determine the hematocrit value.
What does hemostasis refer to?
Hemostasis refers to the process of stopping bleeding while maintaining blood flow within blood vessels.
*It has three stages:
1. Vascular Spasm: Blood vessel constriction.
2. Primary Hemostasis: Formation of a temporary platelet plug.
3. Secondary Hemostasis: Stabilization of the plug with a fibrin clot.
What is the correct order of the hemostatic process?
The correct order of the hemostatic process is:
1. Vascular Spasm: Constriction of blood vessels to reduce blood flow.
2. Primary Hemostasis: Formation of a temporary platelet plug.
3. Secondary Hemostasis: Formation of a stable fibrin clot.
4. Fibrinolysis: Breakdown and removal of the clot once healing is complete.
What is the major receptor on platelets that binds to von Willebrand factor (vWF)?
glycoprotein Ib (GpIb). This interaction is crucial for platelet adhesion during primary hemostasis, especially under high shear stress conditions.
How is the extrinsic pathway of coagulation initiated?
The extrinsic pathway is initiated when tissue factor (TF), a protein released by damaged tissues, interacts with factor VII to form the TF-VIIa complex. This complex activates factor X, leading to the cascade that ultimately forms a fibrin clot.
Which enzyme is responsible for breaking down:
plasmin
What does the Partial Thromboplastin Time (PTT) test evaluate?
intrinsic pathway and the common pathway of the coagulation cascade. It measures the time it takes for blood to clot and is used to identify clotting factor deficiencies or monitor anticoagulation therapy (e.g., heparin).
What is the process of breaking down a fibrin clot called?
fibrinolysis. This involves the enzyme plasmin, which breaks down the fibrin mesh to dissolve the clot after the vessel has healed.
What happens in a deficiency of von Willebrand Factor (vWF)?
A deficiency of vWF results in: Impaired platelet adhesion in primary hemostasis. Reduced stability of factor VIII, affecting the intrinsic pathway. A bleeding disorder called von Willebrand disease (vWD).
What best describes primary hemostasis?
The process of forming a temporary platelet plug at the site of blood vessel injury. It involves: Vasoconstriction: Blood vessels narrow to reduce blood flow. Platelet Adhesion: Platelets adhere to exposed collagen, mediated by vWF and GpIb. Platelet Activation: Platelets release granules to recruit and activate more platelets. Platelet Aggregation: Platelets stick together, creating a temporary plug to stop bleeding.
Which step of primary hemostasis is impaired in a patient with a GPIb genetic mutation, prolonged bleeding time, and easy bruising?
The impaired step is platelet adhesion. The GPIb receptor is essential for binding to von Willebrand factor (vWF), anchoring platelets to exposed collagen at the injury site. A mutation in GPIb disrupts this process, leading to prolonged bleeding and easy bruising.
