Hematologic & Immune Disorders Flashcards
Covers hemostasis, blood cell disorders, hypersensitivity, autoimmune diseases, and transplant immunology. (25 cards)
What is hemostasis?
The process that prevents excessive bleeding while maintaining blood flow in circulation, involving vasoconstriction, platelet plug formation, and coagulation cascade activation.
What are the three phases of hemostasis?
1) Vascular phase – Immediate vasoconstriction to reduce blood loss.
2) Platelet phase – Platelets adhere to damaged endothelium, forming a plug.
3) Coagulation phase – Activation of clotting factors leads to fibrin clot formation.
What is the difference between primary and secondary hemostasis?
- Primary hemostasis: Platelet adhesion, activation, and aggregation forming a temporary plug.
- Secondary hemostasis: The coagulation cascade stabilizes the plug with fibrin.
What is Disseminated Intravascular Coagulation (DIC)
A life-threatening condition where excessive clotting depletes clotting factors and platelets, leading to simultaneous thrombosis and hemorrhage.
What causes Disseminated Intravascular Coagulation (DIC)
Sepsis (most common cause)
Trauma, burns, obstetric complications, cancer, severe infections
What are the lab findings in DIC ( Disseminated Intravascular Coagulation)?
↑ D-dimer (due to fibrin breakdown)
↓ Platelet count
↑ PT and aPTT (prolonged clotting times)
↓ Fibrinogen levels
What is the treatment for DIC (Disseminated Intravascular Coagulation)?
Treat underlying cause, supportive therapy (platelet transfusion, fresh frozen plasma), anticoagulants (heparin in some cases)
What is thrombocytopenia? (Low Platelet Count)
A platelet count < 150,000/µL, leading to increased bleeding risk
What are common causes of thrombocytopenia? (Low Platelet Count)
- Bone marrow suppression (chemotherapy, leukemia)
- Immune destruction (ITP, heparin-induced thrombocytopenia)
- Splenic sequestration (liver disease, splenomegaly)
What are signs of thrombocytopenia? (Low Platelet Count)
Petechiae, purpura, mucosal bleeding, prolonged bleeding time.
What is thrombocytosis? (High Platelet Count)
A platelet count > 450,000/µL, increasing the risk of thrombosis.
What are causes of thrombocytosis? (High Platelet Count)
- Primary (essential thrombocythemia) – Bone marrow overproduction.
- Secondary (reactive thrombocytosis) – Infections, inflammation, iron deficiency
What is neutropenia? (Low Neutrophils)
Absolute neutrophil count (ANC) < 1,500/µL, increasing infection risk.
What causes neutropenia? (Low Neutrophils)
- Bone marrow failure (chemotherapy, leukemia)
- Autoimmune disorders
- Severe infections depleting neutrophils
What is leukopenia? (Low WBCs)
A total WBC count < 4,000/µL, often caused by bone marrow failure or viral infections
What is leukocytosis? (High WBCs)
A total WBC count > 11,000/µL, usually due to infection, inflammation, or leukemia.
What is polycythemia?(Increased RBC Count)
Excess RBCs, leading to increased blood viscosity and clot risk
What are the two types of polycythemia? (Increased RBC Count)
1) Primary polycythemia (Polycythemia Vera) – Bone marrow disorder causing excessive RBC production.
2) Secondary polycythemia – Due to chronic hypoxia (e.g., COPD, high altitude)
What are the four types of hypersensitivity reactions?
Type I (Immediate, IgE-mediated) – Allergies, anaphylaxis.
Type II (Cytotoxic, IgG/IgM) – Hemolytic anemia, Graves’ disease.
Type III (Immune Complex) – Lupus, serum sickness.
Type IV (Delayed, T-cell mediated) – Contact dermatitis, TB test
What is the mechanism of Type I hypersensitivity?
Allergen → IgE binds mast cells → Histamine release → Inflammation (e.g., asthma, anaphylaxis)
What is an autoimmune disease?
A disorder where the immune system attacks self-antigens, leading to chronic inflammation
Give examples of common autoimmune diseases.
- Systemic lupus erythematosus (SLE) – Multi-organ involvement.
- Rheumatoid arthritis (RA) – Chronic joint inflammation.
- Type 1 diabetes – Autoimmune destruction of pancreatic β-cells.
- Multiple sclerosis (MS) – CNS myelin destruction
What is the major risk in organ transplantation?
Graft rejection due to immune response against non-self antigens
What are the three types of transplant rejection?
1) Hyperacute rejection (minutes-hours): Pre-formed antibodies against donor tissue.
2) Acute rejection (days-weeks): T-cell mediated immune response.
3) Chronic rejection (months-years): Fibrosis and gradual organ dysfunction
