(35) Intro to haematology Flashcards
1
Q
What is haematology?
A
Biology and pathology of the cells that normally circulate in the blood
2
Q
What is haemopoiesis?
A
The physiological development process that gives rise to the cellular components of blood
3
Q
What can a single multipotent haemopoietic stem cell give rise to?
A
Can divide and differentiate to form different cell lineages that will populate the blood
4
Q
What are the characteristics/features of a haemopoietic stem cell?
A
- differentiation potential for all lineages
- high proliferative potential
- long term activity throughout lifespan of individual
- self renewal
5
Q
Where was experimental proof of the potential of haemopoietic stem cells derived from?
A
From serial murine transplants
Durand & Dziernak 2005
6
Q
What does symmetric self-renewal lead to?
A
- increase stem cell pool
- no generation of differentiated progeny
7
Q
What does asymmetric self-renewal lead to?
A
- maintain stem cell pool
- generation of differentiated progeny
8
Q
What does lack of self-renewal lead to?
A
- deplete stem cell pool
- generation of ONLY differentiated progeny
OR
- maintain stem cell pool
- no differentiated progeny
9
Q
Name 2 types of differentiation that stem cells might undergo
A
- lymphopoiesis
- myelopoiesis
10
Q
What is lymphopoiesis?
A
The generation of lymphocytes, one of the five types of white blood cell
11
Q
What is myelopoiesis?
A
Formation of myeloid leukocytes (myelocytes), including eosinophilic granulocytes, basophilic granulocytes, neutrophilic granulocytes, and monocytes
12
Q
What is produced in asymmetric division?
A
- a stem cell
AND - a differentiated daughter cells
13
Q
What are the 2 main haemopoietic lineages?
A
- myeloid
- lymphoid
14
Q
Give examples of myeloid cells
A
- granulocytes (WBCs)
- erythrocytes (RBCs)
- platelets
15
Q
Give examples of lymphoid cells
A
- B-lymphocytes (WBCs)
- T-lymphocytes (WBCs)
16
Q
In haemopoiesis, a multipotent stem cell gives rise to myeloid and lymphoid lineage. What types of stem cells are these?
A
Pluripotent stem cells
17
Q
Multipotent stem cells gives rise to pluripotent stem cells which give rise to what?
A
Committed stem cells
Then mature cells
18
Q
Give examples of types of mature cells
A
- red cells
- platelets
- neutrophils
- monocytes
- eosinophils
- basophils
- lymphocytes
19
Q
Are mature blood cells infinite or finite?
A
Finite
eg. an erythrocyte has a life span of about 120 days
20
Q
What is the life span of an erythrocyte?
A
120 days
21
Q
What is the life span of a neutrophil?
A
Lasts only 6-10 hours in the blood stream
22
Q
At what day does haemopoiesis start in the embryo?
A
Day 27
23
Q
In which region does haemopoiesis start?
A
In the aorta gonad mesonephros region
24
Q
Where do haematopoietic stem cells migrate to in the foetus?
A
To the foetal liver, which becomes the subsequent site of haemopoiesis
25
Describe haemopoiesis in the foetus
Starts at day 27 in the aorto-gonad-mesonephros region, expands rapidly at day 35 and then disappears at day 40. Disappearance correlates with migration of the stem cells to foetal liver = new site of haemopoiesis
26
State the functions of blood cells
- oxygen transport
- coagulation
- immune response to infection
- immune response to abnormal cells (senescent, malignant etc)
27
Describe the appearance of erythrocytes
- bi-concanve discs
| - 7.5um diameter
28
How many red cells do we have?
333,200 x 10^6
29
What do erythrocytes contain?
Haemoglobin
30
What is reduced red cells?
Anaemia
31
What is raised red cells?
Polycythaemia
32
What is relative polycythaemia?
When plasma volume is reduced
33
What are the functions of leukocytes (white blood cells)?
Immunity and host defence
34
Name 3 types of leukocytes
- granulocytes
- lymphocytes
- monocytes
35
Give a feature of granulocytes
Have cytoplasmic granules
36
Name 3 types of granulocyte
- neutrophils
- eosinophils
- basophils
37
What is the most common white blood cells in adult blood?
Neutrophil (10x10^9 per litre)
38
What are neutrophils?
Phagocytes
39
What is increased numbers of neutrophils called?
Neutrophilia
40
What is decreased numbers of neutrophils called?
Neutropenia
41
What may be a cause of neutropenia?
Side effect of a drug
42
Why might you get neutrophilia?
- bacterial infection
| - inflammation
43
What is increased number of eosinophils called?
Eosinophilia
44
Why might you get eosinophilia?
- parasitic infection
| - allergies
45
Are basophils common or rare?
Rare
Part of primitive immune system
46
What is increased number of basophils called?
Basophilia
47
When might you get basophilia?
In chronic myeloid leukaemia
48
What are monocytes?
Phagocytic and antigen-presenting cells
49
Monocytes migrate to tissues and are then identified as what?
Macrophages
or histiocytes
50
Give 2 specific types of macrophage
- Kupffer cells in liver
| - Langerhans cells in skin
51
What is increased numbers of monocytes called?
Monocytosis
52
When might you get monocytosis?
In tuberculosis
53
Name 4 types of lymphocyte
- natural killer cells
- B lymphocytes
- T lymphocytes
- plasma cells
54
Natural killers (NK) are part of what immune system?
Innate immune system
55
Describe natural killer cells
Large granular lymphocytes
56
What do natural killer cells recognise?
Non-self eg. cells, viruses
57
B-lymphocytes are part of what immune system?
Adaptive immune system
Humoral immunity
58
What do B cells do?
Rearrange the immunoglobin genes to enable antigen specific antibody production
59
T-lymphocytes are part of what immune system?
Adaptive immune system
Cell-mediated immunity
60
What do T cells do?
- rearrange the T cell antigen receptor
- target specific cytotoxicity
- interact with B cells, macrophages
- regulate immune responses
61
What is increased numbers of lymphocytes called?
Lymphocytosis
62
When might you get lymphocytosis?
- atypical lymphocytes of glandular fever (infectious mononucleosis)
- chronic lymphocytic leukaemia
63
What is decreased numbers of lymphocytes called?
Lymphopenia
64
When might you get lymphopenia?
Post bone marrow transplant
65
What is an increased number of plasma cells called?
Plasmacytosis
66
When might you get plasmacytosis?
- infection
| - myeloma
67
What are platelets derived from?
Bone marrow megakaryocytes
68
How many platelets do we have?
200 x10^9 per litre
69
What is the purpose of platelets?
They form part of the blood clotting system - aggregate to plug holes in damaged blood vessels
70
Platelets form part of the blood clotting system together with what?
Soluble plasma clotting factors and endothelial cells
71
What are the 4 main subdivisions of haematology clinical practices?
- coagulation
- malignant
- non-malignant
- transfusion
72
Name 3 types of diagnostic test
- full blood count
- blood film (or "smear")
- coagulation screen
73
What is included in the FBC diagnostic test?
- haemoglobin concentration
- red cell parameters (MCV, MCH)
- white cell count (WCC)
- platelet count
74
What do coagulation screen tests measure?
The time taken for a clot to form when plasma is mixed with specified reagents
75
In a coagulation screen, various parts of the coagulation cascade can be assayed including..
- prothrombin time
- activated partial thromboplastin time
- thrombin time
76
How is a bone marrow aspirate done?
Under local anaesthetic, liquid marrow is aspirated from the posterior iliac crest of the pelvis and a trephine core biopsy is then taken with a hollow needle
77
What is a trephine?
A hole saw used in surgery to remove a circle of tissue or bone.
78
Where is a bone marrow aspirate taken from?
Posterior iliac crest of the pelvis
79
How do you ensure an accurate FBC and correct interpretation of a blood film?
- appropriate sample from patient
- collected into EDTA anti coagulated blood
- samples get to lab promptly
80
Why is it important that blood samples get to the lab quickly?
Since EDTA artefact can affect the results
81
A blood samples should be collected into EDTA anti coagulated blood. What are the specific requirements?
- mixed well
- [K2EDTA] = 1.5 - 2.2 mg ml-1
- blood should be filled to the line on tube ed
82
Why might test results vary due to technical failure?
- clotted sample
| - variation in reagents
83
Why might test results vary due to the individuals?
- intra-individual eg. diurnal variation in cortisol levels
| - inter-indvidiual eg. platelet count
84
How is a reference range established?
- define the reference population
- reference population should be relevant to the test population
- consider if separate ranges are required for adults vs. children, men vs. women etc
- determine the expected range of inter-individual variation
85
What is a reference range?
The set of values for a given test that incorporates 95% of the normal population
- determined by collecting data from vast numbers of lab tests
86
What is sensitivity?
The proportion of abnormal results correctly classified by the test
- expresses the ability to detect a true abnormality
87
What is the formula for sensitivity?
TP/(TP+FN)
88
What is specificity?
The proportion of normal results correctly classified by the test
- expresses the ability to exclude an abnormal result in a healthy person
89
What is the formula for specificity?
TN/(TN+FP)
90
What is the normal range of haemoglobin?
Male = 135-180g/L
Female = 115-160g/L
91
What is the normal range for WBC?
4.00-11.00 x10^9/L
92
What should you be alert to when interpreting FBC?
Technical problems eg. thrombocytopenia (may be real, may be artefact)
93
What happens when FBC comes back with abnormal results?
- flagged by lab
- may trigger additional tests e.g.. blood film
- if serious = lab staff alert on-call doctors eg. new leukaemia
94
An FBC may be outside of normal range but appropriate for clinical situation. Give examples
- post-splenectomy mild lymphocytosis
| - 3 months post-bone marrow transplant lymphopenia
95
How is microcytic hypochromic anaemia classified according to MCV and MCH?
- MCV
96
How is normocytic normochromic anaemia classified according to MCV and MCH?
- MCV 80-95fl
| - MCH >27pg
97
How is macrocytic anaemia classified according to MCV?
- MCV > 95fl
98
What are the other features of microcytic hypochromic anaemia?
- iron deficiency
- thalassaemia
- anaemia of chronic disease (some)
- lead poisoning
- sideroblastic anaemia (some cases)
99
What are the other features of normocytic normochromic anaemia?
- many haemolytic anaemias
- anaemia of chronic disease (some cases)
- after acute blood loss
- renal disease
- mixed deficiencies
- bone marrow failure (eg. post-chemotherapy, infiltration by carcinoma etc)
100
Macrocytic anaemia can be divided into which 2 types?
- megaloblastic
| - non-megaloblastic
101
What are the causes of megaloblastic macrocytic anaemia?
Vitamin B12 or folate deficiency
102
What are the causes of non-megaloblastic macrocytic anaemia?
- alcohol
- liver disease
- myelodysplasia
- aplastic anaemia
etc
103
How do the red cells appear in iron deficiency?
- small, pale (low MCV and MCH)
- variable size and shape
- some long thin "pencil" cells
104
What is seen in B12 deficiency on a blood film?
Hypersegmented neutrophils and oval macrophages
