Introduction to Haematology Flashcards
What are the main components of blood?
Red blood cells
Plasma
Buffy coat
What blood products are found in the plasma?
Clotting/coagulation factors
Antibodies
Albumin
What blood products are found in the buffy coat?
Platelets
White cells
What are the main functions of blood?
Transport- gases in red cells, nutrients, waste and messages in plasma
Maintenance of vascular integrity- prevention of leaks (platelets and clotting factors), prevention of blockages (anticoagulants and fibrinolytics)
Protection from pathogens (phagocytosis, antigen recognition)
What are the main characteristics of stem cells?
- Totipotent
- Self-renewal
- Home to marrow niche (specifically Cxcr4 (antagonist plerixafor))
- Binary fission and flux through differentiation pathways amplify numbers
- Flux regulated by hormones / growth factors (Some used therapeutically (erythropoietin, g-csf, thrombopoietin agonists))
- Stem cell properties can now be ‘induced’
Where is bone marrow present?
In almost all bones in children
Regresses with age
Mainly just axial skeleton in elderly
What are the stages in erythroid differentiation?
Erythroblasts
Released into circulation as reticulocytes
Mature to erythrocytes after 24hrs
What hormone drives the production of reticulocytes, where is it made and what is it released in response to?
Erythropoietin
Released from kidneys in response to hypoxia
How are platelets made?
Budded off from megakaryocytes
What are the functions of platelets?
Main role is haemostasis
Small role in immune function
What hormone regulates production of platelets? Where is it produced?
Thrombopoietin
Produced in the liver
What is an excess and deficit of platelets known as?
Excess- thrombocytosis
Deficit- thrombocytopenia
What is the function of neutrophils?
To ingest and destroy pathogens, especially bacteria and fungi
What are the steps in differentiation of neutrophils?
- Blast
- Promyelocyte
- Myelocyte
- Metamyelocyte
- Neutrophil
What is a deficiency of neutrophils known as?
Neutropenia
How do myeloid cells differentiate?
A subset of monocytes migrate into tissues and become either macrophages or dendritic cells
What are the names of the less common myeloid cells?
Eosinophils
Basophils
What is an excess and deficit of lymphocytes known as?
Excess- lymphocytosis
Deficit- lymphopenia
What are the subtypes of lymphocytes?
- B cells– make antibodies (mature in bone marrow)
- T cells – Helper, cytotoxic, regulatory (mature in thymus)
- Natural killer cells
How does differentiation of lymphocytes occur?
Differentiation of lymphocytes into effector cells occur in the secondary lymphoid organs (lymph nodes or mucosal associated lymphoid tissue)
What is the function of an antibody?
To act as an adaptor between pathogens and clearance systems, which is known as opsonisation
How does positive and negative selection of B cells occur?
Positive and negative selection of B cells occurs 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. B cells that have been positively selected are exported to the periphery
What are the two classes of human leukocyte antigens?
Class I: displays internal antigens on all nucleated cells
Class II: displays antigens eaten by professional antigen presenting cells
What is the normal range for haemoglobin in males?
135-170 g/L
