PATH2220 Study Guide - Final Guide: Volume Overload, Leukocytosis, B-Cell Chronic Lymphocytic Leukemia
Haematology
What is Haematology?
• Science/medicine of blood
• Disorders of the blood/bone marrow
• Blood transfusion
Blood:
• Cells, water, proteins and electrolytes
• Cells → erythrocytes, leukocytes, thrombocytes
• Water → plasma
• Average volume → 5L
Erythrocytes:
• Made in bone marrow through erythropoiesis
• Small flexible biconcave disc shaped cells
• No nucleus
• Membrane made up of lipids and proteins
o Membrane must be deformable and stabile
o Lipid bilayer with embedded proteins
o Membrane proteins → 50%
▪ Peripheral → membrane elasticity
▪ Integral → embedded with lipids
• Carry haemoglobin (Hb) to tissues
• Require iron, folate, vitamin B12 and EPO
• Lifespan of 120 days
• Cannot reproduce
• No synthetic activities
• Contains no organelles
• Removed in reticulo-endothelial system
• Haemoglobin
o Each red cell contains 640x106 molecules of Hb
o Hb → haem attached to globin chains
o Haem → made in mitochondria, contains Fe2+ → broken down to
bilirubin and excreted by the liver
o Globin → 4 polypeptide chains
▪ HbA → 22 → 98%
▪ Defects in globin → thalassaemia, sickle cell disease
▪ Degraded down to amino acids and returned to body pool
• Erythropoiesis
o Under influence of erythropoietin → hormone produced in
kidneys
o Stages of development in bone marrow
▪ Cell becomes smaller
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▪ Nucleus matures → chromatin condensation
▪ Cytoplasm gains haemoglobin
▪ Nucleus extruded to produce mature RBC
▪ Anuclear biconcave disc with flexible membrane
o 200 billion red blood cells made each day
• Requirements for erythropoiesis
o Erythropoietin (EPO)
▪ Regulates red blood cell production
▪ 90% produced in kidneys
▪ Stimulus to EPO production is renal O2 tension → anaemia,
low atmosphere O2, defective cardiac/pulmonary function
o Iron
▪ Integral part of haemoglobin
▪ From diet → 5-10% absorbed in upper small bowel
▪ Transported to marrow bound to transferrin
▪ Excess stored in macrophages as ferratin
▪ Require 1-2mg/day
▪ Varies by age and gender
o Vitamin B12
▪ Required for nuclear maturation
▪ From diet → animal products
▪ Absorbed in ileum → requires instrinsic factor
▪ Large stores last years
o Folate
▪ From fruit, vegetables
▪ Absorbed in upper small bowel
▪ Small stores → 3 months
▪ Deficiencies result in macrocytic anaemia
• Red cell metabolism
o Glucose is metabolized in RBCs by anaerobic glycolysis
o Embden-Meyerhof pathway
o Reduced RBC lifespan/increased rate of RBC destruction →
haemolysis
Leukocytes:
• Eosinophils
o 1-5% of leukocytes
o 2-lobed nucleus with large orange granules
o Circulation time → 3-8 hours
o Involved in allergy, parasitic infection
• Basophils
o <1% of white cells
o Deep purple-black granules overlie nucleus
o Function unknown
• Monocytes
o 2-8% of WBC
o 20-40hrs in blood
o Mature to macrophage in tissues
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Document Summary
What is haematology: science/medicine of blood, disorders of the blood/bone marrow, blood transfusion. Blood: cells, water, proteins and electrolytes, cells erythrocytes, leukocytes, thrombocytes, water plasma, average volume 5l. Blood transfusions: blood products, packed red blood cells, platelets, fresh frozen plasma, immunoglobulins, blood donation, collection of blood, separation and blood grouping, screening for infectious agents. Indications: acute blood loss, symptomatic, bone marrow failure, thrombocytopenia, immune deficiencies, risks, wrong blood group, volume overload, fever, immune reaction, infection. Infectious mononucleosis (ebv: lymphocytes reactive to viral infection, altered lymphocyte morphology, monocytosis, uncommon, causes, chronic infection, tuberculosis, malaria, eosinophilia. Increased in allergic conditions asthma, eczema, hay- fever: parasitic infections, drug reactions, basophilia, very rare almost always malignant, chronic myeloid leukaemia. Immunophenotyping antigen expression by flow cytometry used to characterize: many genetic abnormalities, treatment chemotherapy, transplantation, chronic leukaemia, malignant proliferation of mature lymphoid or myeloid cells, chronic lymphocytic leukaemia.
