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Flashcards in Introduction to haematology Deck (46):
1

What is haematopoiesis?

- The physiological developmental process that gives rise to the cellular components of blood

- A single multipotent haemopoietic stem cell can divide and differentiate to form different cell lineages that will populate the blood

2

What is a haemopoietic stem cell?

- Differentiation potential for all lineages
- High proliferative potential
- Long term activity throughout the lifespan of the individual
- Self renewal

3

What is symmetric self-renewal?

Increase stem cell pool – NO generation of differentiated progeny

4

What is asymmetric self-renewal?

Maintain stem cell pool – generation of differentiate progeny.

5

What is lack of self-renewal?

Deplete stem cell pool – generation of ONLY differentiated progeny

OR

Maintain stem cell pool – NO differentiated progeny

6

What are the two haemopoietic lineages?

- Myeloid
- Lymphoid

7

At what point in human development does heamopoiesis start?

Day 27

8

Where does heamopoiesis start?

In the aorta-gonado-mesonephros region,
expands rapidly at day 35, then disappear at day 40.

9

Why does the aorta-gonado-mesonephros region disappear?

This disappearance correlates with the migration of these hematopoietic stem cells to the foetal liver, which becomes the subsequent site of haemopoiesis.

10

What are the features of erythrocytes?

Bi-concave discs, 7.5 µM diameter

11

What is the lifespan of an erythrocyte?

120 days

12

What is anaemia?

Reduced erythrocytes

13

What is polycythaemia?

Abnormally raised erythrocytes

14

What is relative polycythaemia?

Plasma volume is reduced so erythrocytes appear raised

15

What are granulocytes?

Have cytoplasmic granules (neutrophils, eosinophils, basophils)

16

What is the function of neutrophils?

Phagocytes

17

What is neutrophilia?

Increased numbers of neutrophils

18

Why might neutrophil levels be increased?

Bacterial infection and inflammation

19

What is the lifespan of neutrophils?

A few hours

20

What is neutropenia?

Decreased numbers of neutrophils

21

Why would eosinophil levels be increased?

- Parasitic infection
- Allergies

22

Why might basophil levels be increased?

CML

23

What are monocytes?

- Phagocytic & antigen-presenting cells

- Migrate to tissues & are then identified as “macrophages” or “histiocytes”
e.g. Kupffer cells in liver
e.g. Langerhans cells in skin

24

What is monocytosis and why might it occur?

Increased numbers of monocytes. Can happen in TB.

25

What is the function of NK cells?

- Recognise “non-self”
e.g. Cells, viruses

- Large granular lymphocytes

26

What are B-lymphocytes?

- Adaptive immune system
- rearrange the immunoglobulin genes to enable antigen specific antibody production
- humoral immunity

27

What are T-lymphocytes?

- Adaptive immune system
- rearrange the T-cell antigen receptor
- cell-mediated immunity
- target specific cytotoxicity
- Interact with B cells, macrophages
- Regulate immune responses

28

What is lymphocytosis and why might it occur?

Increased numbers of lymphocytes.

e.g. atypical lymphocytes of glandular fever (infectious mononucleosis)
e.g. Chronic lymphocytic leukaemia

29

What is lymphopenia and why might it occur?

Decreased numbers of lymphocytes.

e.g. post bone marrow transplant

30

What is plasmocytosis and why might it occur?

Increased numbers of plasma cells

e.g. infection, myeloma

31

What are platelets derived from?

Bone marrow megakaryocytes

32

What measures are included in a full blood count?

- Haemoglobin concentration
- Red cell parameters
- MCV (mean cell volume)
- MCH (mean cell Hb)
- White Cell Count (WCC)
- Platelet Count

33

What measures are included in a coagulation test?

- Prothrombin Time
- Activated Partial Thromboplastin Time
- Thrombin Time

34

How is a bone marrow aspirate & trephine performed?

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.

35

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 versus children, men versus women, and so forth.
- Determine the expected range of interindividual variation

36

What is a reference range?

The set of values for a given test that incorporates 95% of the normal population

37

What percentage of results fall within the reference range?

95%

38

What is sensitivity?

- The proportion of abnormal results correctly classified by the test.
- Expresses the ability to detect a true abnormality

39

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

40

In what situation might an abnormal lymphocyte count be expected?

- Post-splenectomy, mild lymphocytosis
- 3 months post-bone marrow transplant lymphopenia

41

What is microcytic anaemia?

MCV

42

What are the causes of microcytic anaemia?

- Iron deficiency
- Thalassaemia
- Anaemia of chronic disease (some)
- Lead poisonng
- Sideroblastic anaemia (some cases)

43

What is normocytic anaemia?

MCV 80-95 fl & MCH ≥ 27 pg

44

What are the causes of normocytic anaemia?

- Many haemolytic anaemias
- Anaemia of chronic disease (some cases)
- After acute blood loss
- Renal disease
- Mixed deficiencies
- Bone marrow failure (e.g. post-chemotherapy, infitration by carcinoma etc)

45

What is macrocytic anaemia?

MCV >95 fl

46

What are the causes of macrocytic anaemia?

Megaloblastic: Vitamin B12 or folate deficiency
Non-megaloblastic: alcohol, liver disease, myelodysplasia, aplastic anaemia etc

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