Haem Flashcards
What does the bone marrow do?
Produces blood cells (red cells, white cells, and platelets).
Manages red cell disorders, white cell disorders, platelet disorders, clotting, and transfusion.
What are the types of white blood cells?
Neutrophils
Eosinophils
Basophils
Monocytes
Lymphocytes
What are the common causes of anaemia?
Loss: Bleeding
Destruction
Reduced production
Diagnosis involves history, examination, and tests like blood film, automated counts, MCV, and Hct.
How is anaemia classified by MCV (Mean Corpuscular Volume)?
Normocytic:* Anaemia of chronic disease, Mixed picture*
Microcyti**c:* Chronic blood loss, iron deficiency, thalassaemia, spherocytosis*
Macrocy**tic:* B12/F*olate deficiency, thyroid issues, alcohol, reticulocytes (immature cells).
What are the mechanisms of anaemia due to destruction?
Intravascular: Schistocytes, toxic damage, complement, mechanical causes.
Haptoglobin overwhelmed, iron accumulation.
Extravascular: Red cells are consumed by macrophages in the liver/spleen.
Bound immunoglobulins or physical issues like spherocytes.
What are the tests used to diagnose anaemia?
Blood film
Automated counts
Mean Corpuscular Volume (MCV)
Haematocrit (Hct)
What are the key features of microcytic anaemia?
Chronic blood loss leading to iron deficiency.
Thalassaemia, sickle cell disease.
Spherocytosis.
What are the key features of macrocytic anaemia?
B12 or folate deficiency.
Thyroid issues.
Alcohol-related liver disease.
Presence of reticulocytes (immature red cells).
How do white cells function in the immune system?
Neutrophils: Fight bacterial infections.
Eosinophils: Combat parasites and allergens.
Basophils: Release histamine in allergic reactions.
Monocytes: Phagocytosis and antigen presentation.
Lymphocytes: Include T cells, B cells, and natural killer cells for adaptive immunity.
What are the main components of clotting?
Platelets
Coagulation factors
Fibrinogen
Endothelial cells
What are red blood cells responsible for?
Transporting oxygen via haemoglobin.
Removing carbon dioxide from the body.
What is the lifespan of a red blood cell?
Approximately 120 days.
How is haemoglobin structured?
Composed of four protein subunits (two alpha and two beta chains).
Each subunit contains a haem group with iron for oxygen binding.
What is erythropoiesis?
The process of producing red blood cells in the bone marrow.
Stimulated by erythropoietin from the kidneys.
What is the role of platelets in haemostasis?
Aggregate at the site of vascular injury.
Form a platelet plug to prevent bleeding.
Release granules that recruit other platelets and coagulation factors.
What is the function of lymphocytes?
T cells: Cell-mediated immunity.
B cells: Produce antibodies for humoral immunity.
Natural killer cells: Destroy virus-infected and cancerous cells.
What is the difference between innate and adaptive immunity?
Innate: Immediate, non-specific defense (e.g., neutrophils, macrophages).
Adaptive: Specific, delayed response (e.g., T cells, B cells).
What is the role of neutrophils?
First responders to bacterial infections.
Perform phagocytosis to engulf and destroy pathogens.
What causes eosinophilia?
Allergic reactions.
Parasitic infections.
Certain cancers (e.g., Hodgkin lymphoma).
What is thrombocytopenia?
Low platelet count.
Causes include bone marrow failure, increased destruction, or sequestration in the spleen.
What is thrombocytosis?
High platelet count.
May be reactive (due to inflammation) or related to myeloproliferative disorders.
What is the function of basophils?
Release histamine and other mediators during allergic reactions.
What are the primary causes of neutropenia?
Chemotherapy.
Bone marrow suppression.
Severe infections.
What is the function of monocytes?
Phagocytosis of pathogens and debris.
Differentiate into macrophages in tissues.
Present antigens to lymphocytes.
What are reticulocytes?
Immature red blood cells.
Increased in response to anaemia or blood loss.
What is pancytopenia?
Reduction in red cells, white cells, and platelets.
Causes include bone marrow failure and aplastic anaemia.
What is sickle cell disease?
A genetic disorder causing abnormal haemoglobin (HbS).
Leads to sickling of red cells, vaso-occlusion, and haemolysis.
What is thalassaemia?
A group of inherited blood disorders.
Results in reduced or absent production of one of the globin chains in haemoglobin.
What are schistocytes?
Fragmented red blood cells.
Seen in conditions like thrombotic microangiopathies and DIC.
What is the role of fibrinogen in clotting?
Precursor to fibrin, which stabilizes the platelet plug.
Converted by thrombin during coagulation.
What is disseminated intravascular coagulation (DIC)?
A condition of widespread clotting and bleeding.
Triggered by sepsis, trauma, or malignancies.
What are the symptoms of iron-deficiency anaemia?
Fatigue
Pallor
Breathlessness
Brittle nails, hair loss.
What are the common causes of vitamin B12 deficiency?
Pernicious anaemia.
Dietary deficiency (e.g., vegan diet).
Malabsorption (e.g., Crohn’s disease).
What are the stages of haemostasis?
Vascular spasm.
Platelet plug formation.
Coagulation (fibrin clot formation).
What are Howell-Jolly bodies?
Nuclear remnants in red blood cells.
Seen in asplenia or hyposplenism.
What is the Coombs test used for?
Detects antibodies against red blood cells.
Used to diagnose haemolytic anaemias.
What are the functions of the spleen in haematology?
Filters abnormal or old red cells.
Immune surveillance.
Stores platelets and white cells.
What are the causes of splenomegaly?
Infections (e.g., EBV).
Haematological disorders (e.g., lymphoma).
Portal hypertension.
What is haemophilia?
A genetic disorder causing a deficiency in clotting factors VIII (haemophilia A) or IX (haemophilia B).
What are the symptoms of haemophilia?
Easy bruising.
Prolonged bleeding.
Haemarthrosis (bleeding into joints).
What is von Willebrand disease?
A bleeding disorder caused by deficiency or dysfunction of von Willebrand factor.
Impairs platelet adhesion and coagulation.
What is the role of erythropoietin?
Stimulates red blood cell production.
Released by the kidneys in response to hypoxia.
What is the significance of haematocrit?
The percentage of blood volume occupied by red blood cells.
Used to evaluate anaemia and polycythaemia.
What is the normal lifespan of platelets?
7 to 10 days.
What is polycythaemia?
Increased red blood cell mass.
Causes include primary (polycythaemia vera) or secondary (hypoxia, EPO-producing tumours).
What are the functions of the lymphatic system?
Drains excess interstitial fluid.
Transports dietary lipids.
Facilitates immune responses.
What is the role of transfusion therapy?
To replace lost blood components.
Correct deficiencies (e.g., anaemia, clotting factors).
What are the indications for platelet transfusion?
Thrombocytopenia with active bleeding.
Prevention of bleeding in severely low platelet counts.
What are the complications of transfusion therapy?
Allergic reactions.
Febrile non-haemolytic reactions.
Haemolysis.
Infection transmission.
What is aplastic anaemia?
A condition of bone marrow failure.
Causes pancytopenia (low red cells, white cells, and platelets).
Can be caused by autoimmune issues, toxins, or infections.
What is the function of the coagulation cascade?
To form a stable fibrin clot.
Involves intrinsic, extrinsic, and common pathways.
What is the intrinsic pathway in coagulation?
Activated by damage to blood vessels.
Involves factors XII, XI, IX, and VIII.
What is the extrinsic pathway in coagulation?
Triggered by external trauma and exposure to tissue factor.
Involves factor VII.
What is the common pathway in coagulation?
Converges from intrinsic and extrinsic pathways.
Involves factors X, V, II (prothrombin), and I (fibrinogen).
What are the lab tests for coagulation disorders?
Prothrombin Time (PT)
Activated Partial Thromboplastin Time (APTT)
Fibrinogen levels
D-dimer test
What is the D-dimer test used for?
To detect fibrin degradation products.
Indicates clot formation and breakdown, e.g., in DVT or PE.
What is a thrombus?
A blood clot formed within a blood vessel.
Can cause vessel obstruction or embolization.
What is an embolism?
A clot or other material that travels and obstructs a distant blood vessel.
Commonly caused by thrombi, fat, or air.
What are the symptoms of deep vein thrombosis (DVT)?
Swelling in one leg.
Pain or tenderness.
Redness or warmth over the affected area.
What is the role of anticoagulants?
To prevent clot formation or extension.
Examples include warfarin, heparin, and DOACs.
What is warfarin?
An oral anticoagulant.
Inhibits vitamin K-dependent clotting factors (II, VII, IX, X).
What is the mechanism of action of heparin?
Activates antithrombin III.
Inhibits thrombin and factor Xa.
What are Direct Oral Anticoagulants (DOACs)?
Include drugs like rivaroxaban, apixaban, and dabigatran.
Inhibit specific clotting factors (e.g., Xa or thrombin).
What is the purpose of thrombolytic therapy?
To dissolve clots in conditions like stroke or myocardial infarction.
Uses drugs like alteplase.
What are the signs of haemolytic anaemia?
Jaundice.
Dark urine.
Splenomegaly.
What is hereditary spherocytosis?
A genetic condition causing defective red cell membranes.
Leads to spherical red cells and haemolysis.
What are the causes of macrocytosis?
B12 or folate deficiency.
Liver disease.
Hypothyroidism.
What is megaloblastic anaemia?
A type of macrocytic anaemia caused by impaired DNA synthesis.
Often due to B12 or folate deficiency.
What is the role of folate in red cell production?
Essential for DNA synthesis.
Deficiency leads to megaloblastic changes.
What is the role of vitamin B12 in haematology?
Necessary for DNA synthesis and red blood cell production.
Deficiency causes macrocytic anaemia and neurological symptoms.
What are the types of transfusion reactions?
Febrile non-haemolytic reactions.
Allergic reactions.
Haemolytic reactions.
Infection transmission.
What is haemosiderosis?
Iron overload due to repeated blood transfusions.
Can damage organs like the liver and heart.
What is the significance of a blood film?
Visualizes blood cell morphology.
Helps diagnose conditions like anaemia, leukemia, and malaria.
What is leukocytosis?
An elevated white blood cell count.
Common in infections, inflammation, or malignancies.
What is leukopenia?
A low white blood cell count.
Causes include bone marrow suppression, infections, and autoimmune disorders.
