Introduction to Haematology Flashcards
What is haematology?
Investigations and management of blood and bone marrow
What are the blood components and products?
Plasma - clotting or anticoagulant factors, albumin and antibodies
Buffy coat - platelets, white cells or leucocytes
Red blood cells
What are the functions of blood?
Plasma carries nutrients, waste and messages
Prevention of leaks
Prevention of blockages
Phagocytosis + killing - granulocytes/ monocytes
Antigen recognition and antibody forming
What is the pathogenesis of haematological abnormalities?
High levels - increased rate of production
Low levels - decreased rate of production and increased rate of loss
Altered function
Where does hamatopoisis happen?
Bone marrow
From stem cells
What is the potential products of haematopoiesis?
Erythrocyte, platelets, neutrophil, monocyte, basophil, eosinophil and lymphocyte
And other
Describe stem cells
Totipotent, self-renewal, home to marrow niche, binary function and flux through differentiation pathways amplify numbers
Flux regulated by hormones and growth factors
Where is bone marrow found?
Most bones in children
Axial in elderly
Describe erythroid differentiation
Erythroblast - reticulocyte - erythrocyte
Erythropoietin made in kidney in response to hypoxia
Reticulocyte count is a measure of red cell production
What are the causes of anaemia?
Decreased production
Deficiency in haematinics - iron, folate and vitamin B12
Congenital - thalassemia
Increased loss in bleeding and haemolysis
Describe red cells
Microcytes and macrocytes
Polychromasia
Burr cells in renal failure
Can make 10g/L/day
What cell makes platelets?
Megakaryocyte
What do platelets do?
Haemostasis and immune
Produced by thrombopoietin in liver and regulation by platelet mass feedback
Lifespan is 7 days
Describe platelets in pathology
Thrombocytosis
Thrombocytopenia - marrow failure and immune destruction
Altered function - aspirin, clopidogrel, abciximab
Describe neutrophils
Ingest and destroy pathogens, esp bacteria and fungi
Interleukins and CSFs - granulocyte-colony stimulating factor
Regulation by immune responses
Lifespan is 1-2 days
Describe neutrophilia
Production regulated by granulocyte-colony stimulating factor
Infection and inflammation
G-CSF used therapeutically
What can cause neutropenia?
Decreased production - drugs and marrow function
Increased consumption - sepsis and autoimmune
Altered function
What is the function of monocytes
Ingest and destroy pathogens, esp bacteria and fungi
Subset of monocytes migrate into tissues and become macrophages or dendritic cells
When are eosinophils incraesed?
Parasites and allergy
Describe lymphocytes
Adaptive, versus innate, immune system
Surface antigens - CD markers
Lymphocytosis - infectious mononucleosis, pertussis and lymphoproliferative disorders
Lymphopenia - usually post-viral
What are the subtypes of lymphocytes?
B cells - makes antibodies
T cells - helper, cytotoxic and regulatory
NK cells
Where are lymphocytes produced?
In bone marrow - B mature in bone marrow and T in thymus
Circulate in blood, lymph and LNs
Differentiate into effector cells in secondary lymphoid organs
What is the adaptive receptor diversity of lymphocytes?
Each T and B cell has a unique surface antigen
Can change to attack a particular type of antigen
What are antibodies?
Adaptors between pathogens and clearance systems - opsonisation
What are different types of repertoire diversity?
Combinational (within each chain), junctional (at join) and combinatorial (between chains) diversity
Mistakes cause lymphoid malignancies
Describe naive B cell
Migrates and becomes naive until it comes into response with a certain antigen
Can either become a plasma cells or undergoes further differentiation within the lymph node (memory B cell or plasma cell)
Describe the positive and negative selection in the bone marrow
If results in a functional receptor the cell is selected to survive - positive
If the receptor recognises self-antigens then its triggered to die - negative
B cells which survive are transported to periphery
What are class I and II HLA?
I - displays internal antigens on all nucleated cells
II - displays antigens eaten by professional antigen presenting cells
How can rheumatoid arthritis affect the blood?
Anaemia, iron deficiency, folate deficiency, immune haemolysis, neutrophilia, immune thrombocytopenia, cytopenia secondary to medication and Felty syndrome
What are some pathological conditions of plasma?
Too much - paraproteins
Too little - clotting factors (haemophilia)
Abnormal function - clotting factors (Von Willebrand disease)
