Intro to haematology

Question 1

Define haematology?

Answer 1

Biology and pathology of the cells that normally circulate in the blood

Question 2

What is meant by haemapoiesis/haematapoiesis?

Answer 2

The physiological developmental process that gives rise to the cellular components of the blood - a single haematopoietic stem cell can divide and differentiate to form different cell lineages that will populate the blood

Question 3

What are the 4 directions a haemapoietic stem cell can take in its first division, how does each affect the stem cell pool?

Answer 3

1) Symmetric self renewal - 2 stem cells formed (increase in stem cell pool)
2) Assymetric self renewal - 1 stem cell and progenitor formed (maintenance of stem cell pool)
3) Lack of self renewal to form 2 progenitors (depletion of stem cell pool)
4) Lack of self renewal - no division (maintenance of stem cell pool)

Question 4

What 2 different cells can a haemapoietic cell divide to form in its first cell division?

Answer 4

1) Another stem cell
2) Progenitor (daughter cell which has undergone an element of differentiation and lost self renewal capacity, can go on to differentiate into any blood cell)

Question 5

What are the 4 properties of a haemapoietic stem cell?

Answer 5

1) Differentiation potential for all lineages
2) High proliferative potential
3) Long term activity throughout the life span of the individual
4) Self renewal ability

Question 6

What are the 2 main haemapoietic lineages?

Answer 6

1) Myeloid

2) Lymphoid

Question 7

What 3 main types of cell does the myeloid line give rise to?

Answer 7

1) Granulocytes (WBCs)
2) Erythrocytes
3) Platelets

Question 8

What 3 main cell types does the lymphoid line give rise to?

Answer 8

1) B lymphocytes
2) T lymphocytes
3) Natural Killer cells

Question 9

What 4 stages of cells are involved in haemapoiesis?

Answer 9

1) Multipotential stem cell
2) Pluripotential stem cell (either moved to myeloid or lymphoid lineage at this point)
3) Committed cells (form 1 type of cell)
4) Mature cells

Question 10

On which day and where in embryogenesis is any sign of haemapoiesis first seen, is this the beginning of haemapoiesis?

Answer 10

Seen in trophoblast at 9 days
Erythroid cells from yolk sac area
This is the first sign of haemapoiesis but is a false start and not the beginning

Question 11

Where does haemapoiesis fully begin in the foetas on what day of embryogenesis?

Answer 11

Starts at day 27

In the aorta gonad mesonephros area

Question 12

On which day of embryogenesis does haemapoiesis at the AGM expand rapidly?

Answer 12

Day 35

Question 13

What happens to haemapoietic activity at the AGM on day 40 of embryogenesis?

Answer 13

Haemapoiesis rapidly disappears from the AGM
Haemapoietic stem cells migrate through the wall of the aorta into the bloodstream and travel to the liver which then becomes the subsequent sight of haemapoiesis

Question 14

What are the 4 roles of blood cells?

Answer 14

1) Oxygen transport
2) Coagulation
3) Immune response to infection
4) Immune response to abnormal cells (senescent, malignant)

Question 15

What is the shape and life span of erythrocytes?

Answer 15

Bi-concave discs (7.5micrometers in diameter)

120 days in blood

Question 16

How many RBCs can be found in the body?

Answer 16

333,200 x 10^6

Question 17

What is the term for reduced red cells?

Answer 17

Anaemia

Question 18

What is the term for raised red cells?

Answer 18

Polycythaemia

Question 19

What is relative polycythaemia?

Answer 19

Red cell count is not abnormally raised but as plasma volume is reduced the red cell count is raised in comparison

Question 20

What are the 3 types of leukocytes (WBCs)?

Answer 20

1) Granulocytes
2) Lymphocytes
3) Monocytes

Question 21

What are the 3 types of granulocytes, what is distinctive about granulocytes?

Answer 21

Have cytoplasmic granules

1) Neutrophils
2) Eosinophils
3) Basophils

Question 22

What is the main action of neutrophils?

Answer 22

Phagocytic cells

Question 23

What is the most common white cell in adult blood?

Answer 23

Neutrophils

Question 24

What is the term for increased numbers of neutrophils?

Answer 24

Neutrophilia

Question 25

In which 2 common situations is neutrophilia likely to occur?

Answer 25

1) Bacterial infection | 2) Inflammation

Question 26

What is the life span of neutrophils?

Answer 26

Only a few hours in the blood

Question 27

What is the term for reduced numbers of neutrophils, when might this occur?

Answer 27

Neutropenia | May occur as a side effect of drugs

Question 28

What is the term for increased numbers of eoisinophils?

Answer 28

Eosinophilia

Question 29

In which 2 situations is eoisinophilia likely to occur?

Answer 29

1) Parasitic infection | 2) Allergies

Question 30

Are basophils abundant in the blood?

Answer 30

No they are a rare cell

Question 31

What is the term for increased numbers of basophils, when may this occur?

Answer 31

Basophilia | Occur in chronic myeloid leukaemia

Question 32

What are the 2 roles of monocytes?

Answer 32

1) Phagocytic cells | 2) Antigen presenting cells

Question 33

What are monocytes identified as once they leave the blood and enter the tissues?

Answer 33

Macrophages or histiocytes

Question 34

Monocytes which migrate into the liver tissue become what?

Answer 34

Kupffer cells in liver

Question 35

Monocytes which migrate into the skin become what?

Answer 35

Langerhans cells in the skin

Question 36

What is the term for increased numbers of monocytes, in which disease specifically would this occur?

Answer 36

Monocytosis | Tuberculosis

Question 37

Are natural killer cells a part of the innate or adaptive immune system?

Answer 37

Innate

Question 38

What type of cell are natural killer cells?

Answer 38

Large granular lymphocytes

Question 39

What is the role of natural killer cells, what do they identify?

Answer 39

Recognise non self - ie abnormal tissue or virus infected cells

Question 40

What is the main function of B lymphocytes, why are they considered part of the adaptive immune system?

Answer 40

Humoral immunity - attack particles within the blood not contained within cells such as bacteria Produce Ag Adaptive as they modify immunoglobulin genes to enable antigen specific antibody production

Question 41

What is the main role of T cells, what 3 roles specifically does this entail?

Answer 41

Cell mediated immunity 1) Target specific cytotoxicity 2) Interact with B cells and macrophages 3) Regulate immune response

Question 42

What is the term for increased numbers of lymphocytes?

Answer 42

Lymphocytosis

Question 43

What is term for reduced numbers of lymphocytes?

Answer 43

Lymphopenia

Question 44

Why are T lymphocytes considered part of the adaptive immune system?

Answer 44

They can rearrange the genes for the T cell receptor to produce an antigen specific receptor

Question 45

In which 2 situations would lymphocytosis occur?

Answer 45

1) Chronic lymphocytic leukaemia | 2) Glandular fever (infective mononucleosis) - get atypical lymphocytes

Question 46

Give an example of a situation where lymphopenia may occur?

Answer 46

Post bone marrow transplant

Question 47

What is the term for increased plasma cells (mature B cells), in which 2 situations may it occur?

Answer 47

Plasmacytosis 1) Infection 2) Myeloma - malignant overproduction of plasma cells

Question 48

Platelets are derived from which cells?

Answer 48

Bone marrow megakaryocytes

Question 49

Where does haemapoiesis occur?

Answer 49

Bone marrow - mature cells then enter blood

Question 50

What are the 4 main subdivisions of haematology in clinical practise?

Answer 50

1) Coagulation 2) Malignant 3) Non malignant eg anaemia, sickle cell disease 4) Transfusion

Question 51

What are the 4 main types of diagnostic tests in haematology?

Answer 51

1) FBC 2) Blood film (or smear) 3) Coagulation screen

Question 52

What are the 5 main aspects of a FBC?

Answer 52

``` 1) Haemaglobin concentration Red cell parameters: 2) Mean cell volume (MCV) 3) Mean cell Hb (MCH) 4) White cell count (WCC) 5) Platelet count ```

Question 53

What is a blood film?

Answer 53

Drop of blood placed on film and smeared to create a monolayer of cells which is viewed down a microscope

Question 54

What is a coagulation screen?

Answer 54

test which measures the time take for a clot to form when plasma is mixed with specified reagents

Question 55

What are the 3 main coagulation screen tests?

Answer 55

1) Prothrombin time 2) Activated partial thromboplastin time 3) Thrombin time

Question 56

How is a bone marrow aspirate performed?

Answer 56

Under local anaesthetic bone marrow is aspirated from the posterior iliac crest of the pelvis and a trephine core biopsy is then taken with a hollow needle

Question 57

For what 3 reasons can test results vary in a healthy person?

Answer 57

1) Technical failure (eg. clotted sample or variation in reagents) 2) Normal but abnormal due to intra-individual variation (eg. diurnal variation of cortisol levels) 3) Normal but abnormal due to inter-individual variation (eg. platelet count can differ between people)

Question 58

What 3 consideration are relevant in establishing a reference range for what is normal in terms of FBC?

Answer 58

1) Define the reference population - should be relevant to the test population 2) Consider if separate ranges are required for adults versus children, men versus women etc. 3) Determine the expected range of inter individual variation

Question 59

What defines the reference rang?

Answer 59

The set of values for a given test which incorporates 95% of the normal population - determined by collecting data from vast numbers of lab test

Question 60

In tests of healthy and diseases subjects which 2 types of results overlap?

Answer 60

1) False negatives | 2) False positive

Question 61

What is sensitivity?

Answer 61

Proportion of abnormal results correctly classified as abnormal by the test - expresses the ability to detect true abnormality

Question 62

What is specificity?

Answer 62

Proportion of normal results correctly classified as normal by the test

Question 63

What is the normal range of Hb in g/L for men and women?

Answer 63

``` Men = 135-180 Women = 115-160 ```

Question 64

What is the normal range of WBC (same for men and women)?

Answer 64

4.00-11.00

Question 65

What is the normal range for platelets (same for men and women)?

Answer 65

150-400

Question 66

What is the normal range for MCV (Same for men and women)?

Answer 66

78-100

Question 67

What is the normal range for MCH (Same for men and women)?

Answer 67

27-32`

Question 68

What would it be necessary to do if you noticed an unexpectedly abnormal result in a patients blood test eg. thrombocytopenia?

Answer 68

Consider technical problems - this may be a real problem, may be an artefact. Could contact the lab to ask if thinks its an artefact

Question 69

Abnormal results may be totally appropriate for the given situation - give 2 situations when an abnormal lymphocyte count would be appropriate?

Answer 69

1) Post splenectomy mild lymphocytosis | 2) 3 months post bone marrow transplant lymphopenia

Question 70

How is microcytic hypochromic anaemia classified?

Answer 70

Low mean cell volume | MCV

Question 71

Give 4 causes of microcytic hypochromic anaemia?

Answer 71

1) Iron deficiency 2) Thalassaemia 3) Anaemia of chronic disease (some) 4) Lead poisoning 5) Sideroblastic anaemia (some cases)

Question 72

What is sideroblastic anaemia?

Answer 72

Sideroblastic anemia or sideroachrestic anemia is a form of anemia in which the bone marrow produces ringed sideroblasts rather than healthy red blood cells

Question 73

How is normocytic anaemia classified?

Answer 73

``` Reduced numbers of erythrocytes Normal mean cell volume MCV - 80-95 fl Normal mean cell Hb MHC - greater than or equal to 27 pg ```

Question 74

Give 6 causes of normocytic anaemia?

Answer 74

1) Many haemolytic anaemias 2) Anaemia of chronic disease 3) After acute blood loss 4) Renal disease 5) Mixed deficiencies - folic acid, B12 & iron 6) Bone marrow failure (eg. post chemo, infiltration by carcinoma etc.)

Question 75

How is macrocytic anaemia classified?

Answer 75

Reduced erythrocytes Increased mean cell volume MCV = >95 fl

Question 76

What is the commonest cause of macrocytic anaemia?

Answer 76

Alcohol abuse

Question 77

What are the 2 types of macrocytic anaemia, what is the difference?

Answer 77

Megaloblastic and non megaloblastic | Megaloblastic is due to inhibition of DNA synthesis in haemapoiesis

Question 78

Give the 2 main causes of megaloblastic macrocytic anaemia?

Answer 78

Vitamin B12 deficiency | Folate deficiency

Question 79

Give the 4 main causes of non-megaloblastic macrocytic anaemia?

Answer 79

1) Alcohol abuse 2) Liver disease 3) Myelodisplasia 4) Aplastic anaemia

Question 80

How would iron deficiency anaemia appear histologically?

Answer 80

Small, pale red cells with variable size and shape eg. long thin 'pencil cells'

Question 81

How would Vitamin B12 deficiencies appear histiologically?

Answer 81

Larger cells | Presence of hypersegmented neutrophils (more than 7 nuclear lobes) and oval macrophages

Question 82

Hypersegmented neutrophils are characteristic of macrocytic anaemia due to what 2 causes?

Answer 82

Vitamin B12 and folic acid deficiency