Basics of Haematology Flashcards
Components of Blood
Plasma, buffy coat and red blood cells
Plasma
Clotting or coagulation factors, albumin, antibodies
Buffy coat
Platelets, white cells or leucocytes
Functions of Blood (Transport)
Red blood cells transport oxygen and carbon dioxide.
Plasma transports nutrients, waste and messages??
Functions of Blood (Maintenance of Vascular Integrity)
Prevention of leaks (platelets and clotting factors)
Prevention of blockages (anticoagulants and fibrinolytics)
Functions of blood (prevention of pathogens)
Phagocytosis and killing (granulocytes and monocytes)
Antigen recognition and antibody formation (lymphocytes)
Haematopoisesis
The process whereby blood cells are made. Pluripotent haematopoietic stem cell to uncommitted stem cells and lymphocyte stem cells (lymphocytes). These can become erythroblasts (erythrocytes), megakarycytes (platelets), myeloid cells (neutrophil, monocyte, basophil)
Stem cells
These are totipotent and undergo self-renewal.
Home to marrow niche
CXCR4 (antagonist plerixafor)
Bone marrow
Present in the bones. Stroma and sinusoids.
Erythroid Differentiation
Erythroblast - reticulocyte - erythrocyte
Erythropoietin
Made in the kidney in response to hypozia
Reticulocyte count
A measure of red cell production
Consequences of anaemia
Poor gas transfer resulting in dyspnoea and fatigue.
What causes anaemia
Decreased production of red cells due to deficiency in haematinics (iron, folate and vitamin B12) or thalassaemia (any of a group of hereditary haemolytic diseases caused by faulty haemoglobin synthesis)
Increased loss due to bleeding or haemolysis
Red Cells
microcytes (an unusually small red blood cell, associated with certain anaemias)
Macrocytes (A macrocytic class of anemia is an anemia (defined as blood with an insufficient concentration of hemoglobin) in which the red blood cells (erythrocytes) are larger than their normal volume)
Burr cells (echinocytes) abnormal cell membrane characterized by many small, evenly spaced thorny projections
Function of platelets
Haemostasis and immune function.
Production of platelets is regulated by
Thrombopoietin which is produced in the liver, regulated by platelet mass feedback. Lifespan is 7 days.
Function of neutrophils
To ingest and destroy pathogens, especially bacteria and fungi
Regulation of neutrophols
Macrophages and Interleukin
Life span of neutrophils
1-2 days
Neutrophil differentiation
Blast cells, promyelocyte, myelocyte, metamyelocyte and neutrophil
Neutrophilia
Raised neutrophils caused by infection (G-CSF) and inflammation
Neutropenia
Decreased neutrophil production due to drugs or marrow failure
Increased consumption (sepsis or autoimmune)
Altered function (chronic granulomatous disease)
Monocytes function
To ingest and destroy pathogens. Subset of monocytes migrate into tissues to become macrophages or dendritic cells.
Monocytosis
Usually associated with neurophilia. Due to mycobacterial infection
Monocytopenia
Mycobacteria in hairy cell leukaemia
Other myeloid cells
Eosinophils and basophils
Lymphocytes
these are adaptive rather than innate. They have immunological memory. Surface antigens: CD markers.
Lymphocytosis
Infectious mononucleosis and pertussis
Lymphopenia
Lymphoma or post-viral
Sub types of lymphocytes
B cells
T cells – Helper, cytotoxic, regulatory
NK cells
Where are lymphocytes produced
B cells mature in bone marrow, T cells in thymus
Antibodies
Adaptors between pathogens and clearance systems ‘Kiss of death’ Opsonisation Fix complement Block binding
Combinatorial diversity
Any V-region combined with any J or D-region then C-region
Junctional Diversity
At any join, additional nucleotides added by enzyme (terminal deoxynucleotidyl transferase, TdT)
Combinatorial diversity between chains
Each alpha chain pairs with a beta chain
Each light chain pairs with a heavy chain
Selection of B cells in the bone marrow
if gene rearrangement results in a functional receptor the cell is selected to survive – positive selection
If the receptor recognises ‘self’ antigens - the cell is triggered to die – negative selection
Human Leucocyte Antigen Class 1
Displays internal antigens on all nucleated cells
HLA Class 2
Displays antigens eaten by professional antigen presenting cells
Diagnostic tools of blood disorders
FBC, Clotting times, bleeding times for platelets, chemical assays (iron, B12, folate), marrow aspirate and trephine biopsy, lymph node biopsy, imaging
Haematology Treatments (Replacement)
Blood
Haematinics
Coagulation factors
Plasma exchange
Haematology Treatments (Drugs)
Cytotoxics Monoclonal antibodies Inhibitors of cellular proliferation Immunosuppressants Inhibitors of coagulation Inhibitors of fibrinolysis
Hypersplenism
Pancytopenia (deficiency of all three cellular components of the blood (red cells, white cells, and platelets).
Hyposplenism
Infections with encapsulated bacteria, red cell changes
Splenomegaly
Infectious -acute eg EBV, CMV -chronic bacterial eg TB, brucella, SBE -chronic parasitic eg malaria, leishmaniasis, schistosomiasis
Haematological-malignant
- various leukaemias and lymphoma
- myeloproliferative disorders
Portal hypertension
Haemolytic disorders
-hereditary spherocytosis, thalassaemia, megaloblastic anaemia, autoimmune
Connective tissue disorders
- SLE
- Felty Syndrome