Haematology (Intro to haematology) Flashcards
What is haematology?
The study of blood
- concerned with the diagnosis and monitoring of diseases of the blood and blood forming organs
What % of blood is cells? What are the 3 types of cell in the blood?
45%
- RBCs
- WBCs
- Platelets
What is the remaining % of blood?
Plasma
What features of RBCs does haematology study?
- Number
- Function
- Size
- Quantity on haemoglobin they carry
What is the most common condition that affects RBCs?
Anemia
What is the result of anemia and the associated symptoms?
- Reduced oxygen carrying capacity of the blood
- lethargy, weakness, dizziness
What are some common causes of anemia?
- Iron deficiency
- Vitamin B12 deficiency
- Maliganacy
- Kidney and liver disease
- Infections
- Inherited conditions e.g sickle cell
What is another name for WBCs? What are the 5 categories?
leukocytes
- lymphocytes
- monocytes
- neutrophils
- basophils
- eosinophils
What is the most common disease of WBCs?
Leukaemia
What can be the cause of a rise or a fall in WBC count?
Rise:
- Infectious disease
- Leukaemia
Fall:
- aplastic anemia (poor bone marrow formation)
- medication e.g chemo
What is the result of low WBCs?
Immunodeficiency
What % of the total WBC count is made of lymphocytes?
20-45%
What is the structure of lymphocytes?
- Mononuclear
- Nucleus is round and regular
- Makes up 90% of cell
- Do not contain granules
What are the functions of lymphocytes?
1) Generation of antibodies by B cells
2) Co-operation in antibody production by Th cells
3) Destruction of viral infected cells by Tc cells
What % of the WBC count is monocytes? What is their structure?
2-10%
- Large mononuclear cells
- kidney shaped nuclei
- Cytoplasm has a ‘ground glass’ appearance due to granules
- May have vacuoles
- Largest WBC
What are the functions of monocytes?
- Phagocytosis
- Participation in inflammation
- Removal of debris
- Release of cytokines e.g IL-2
- Participation in homeostasis - production of tissue factor
What % of WBC count is neutrophils? What is their structure?
40-75%
- Polymorphonuclear (various shape nuclei)
- Granulocytic
- Larger than RBCs
What are the functions of neutrophils?
- Phagocytosis
- Inflammation
- Removal of debris
What % of WBC count is basophils? What is their structure?
<1%
- Granulocytic
- Large amounts of granules
What is the function of basophils?
- Participation in hypersensitivity
- Release of histamine and heparin
What % of WBC count is eosinophils? What is their structure?
1-6%
- Granulocytic
- Nucleus has 2 lobes
What is the function of eosinophils?
- Protection against parasitic infections
- Participation in allergic reactions
- Release of histamine
What is haemostasis?
Group of balanced cellular and molecular processes that aims to minimise blood loss upon vessel damage
What is the name for the loss of blood?
Haemorrhage
- can be life threatening
What is the term for blood clotting?
Thrombosis
- can also be very dangerous if excessive or inappropriately activated
Normal haemostasis relies on what type of cells and what type of proteins?
Platelets and coagulation proteins
What are platelets and what is their structure?
- Small fragments of the cytoplasm of a larger cell called a megakaryocyte found in bone marrow
- Granular
- Small (smaller than RBCs)
- No nucleus
- Circulate for 7-10 days before destruction in spleen and liver
What is the most common way to obtain a blood sample?
Venepuncture of the median cubital vein
- blood collected into a colour coded vacutainer
What does the colour of the vacutainer indicate?
Whether or not anticoagulants are present, and if so which ones
- Choice of vacutainer will depend on the tests to be performed
What are the 2 main methods of obtaining a bone marrow sample?
1) Bone marrow aspiration
- heavy duty needle driven into bone (breast or hip bone)
2) Trephine procedure
- An even more substantial needle used to remove a section of bone from the hip
Once drawn from the body, how quickly will blood clot and into what 2 components?
2-5 minutes
- a semi-solid mass of cells (clot)
- the fluid (serum)
How is separation of the clot from the serum achieved?
Centrifugation
What can the serum be used to measure?
Micro-nutrients e.g iron, vitamin B12 BUT NOT cells, is acellular
Give some examples of anticoagulants and what they do?
Heparin, sodium citrate
- prevent clotting so that cellular components of the blood may be studied
- work by binding calcium ions
Is clotting is prevented and the cells settle or are centrifuged, what is the name for the liquid part and what does it contain?
Plasma
contains clotting factors
The FBC, coagulation tests and immunophenotyping require what different types of anticoagulants?
FBC - EDTA
Coagulation tests - sodium citrate
Immunophenotyping - heparin
Name the common types of haematological lab tests and what each tests for
1) Full blood count
- number/size RBCs, WBC and platelets; haemoglobin levels
2) Blood films:
- staining and microscopic examination of smeared drop of blood or bone marrow
3) Erythrocyte sedimentation rate (ESR)
- measures viscosity of whole blood and gives info on inflammatory disease
4) Coagulation screen
- examines whch area of blood coagulation biochemistry is abnormal
5) Haematinic assays:
- measues concs of ferritin, vitamin B12 and folate - causes of anemia
6) Immunophenotyping:
- flow cytometry to measure characteristics of single cell
7) Haemoglobin-variant detection:
- seperation techniques e.g electophoresis used to detect haemoglobin pathologies
8) Molecular techniques:
- analysis of DNA (PCR) for acquired/inherited mutations for haematological disorders
What 5 things measured in the full blood count?
1) RBC count
2) WBC count
3) Haemoglobin levels (g/L)
4) Hematocrit - proportion of whole blood taken up by blood cells
5) Red blood cell indices:
- mean cell volume (MCV)
- mean cell haemoglobin (MCH)
- Mean cell haemoglobin concentration (MCHC)
Name the 6 major techniques used in haematology and describe briefly what each is used to measure
1) Spectrometry
- measures concentration of a substance
2) Impedance
- the presence of particles e.g RBCs in an an electrolyte solution prevents the flow of a current
- the degree of impedance given indication of the number of cells present
3) Cytochemistry
- detects presence of macromolecules e.g enzymes
4) Flow cytometry
- specially stained cells scatter light from a laser, allowing the size and number of cells to be measured
5) Microscopy
- BMS plays key role as automation is uncommon
6) Immunoassays
- ELISA, latex immunoassay
What does ELISA stand for? Describe in brief how it is performed
Enzyme linked immunosorbent assay
- Antobody specific for protein coats well
- Excess antibody washed away
- Serum added and protein binds to antibody
- Plate washed
- Addition of antibody conjugated to enzyme (HRP) - binds to protein
- Plate washed
- Substrate reacted with enzyme to give coloured product
What 4 tests are performed in a coagulation screen?
1) Prothrombin time (PT)
2) Activated partial thromboplastin time (APTT)
3) Thrombin time (TT)
4) Fibrinogen
