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MEH > Haematology > Flashcards

Haematology Flashcards

1
Q

Define Haemopoiesis

A

Production of blood cells in the bone marrow

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2
Q

Describe the Reticuloendothelial System (RES)

A

RES= network in blood and tissues which part of the immune system containing phagocytic cells
Cells of the RES can identify and mount an appropriate immune response to foreign antigens
Main organs= spleen and liver
All blood passes through the spleen so damaged/ old RBCs can be disposed of

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3
Q

Definition of Neutrophil

A

first responder phagocyte, commonest white cell, essential part of innate immune system
once mature- circulate in bloodstream then invade tissue (1-4 days)
controlled by the hormone G-CSF

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4
Q

Describe the function of the hormone G-CSF

A
  • increase production of neutrophils
  • decrease time to release mature cells from bone marrow
  • enhances chemotaxis
  • enhances phagocytosis & killing of pathogens
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5
Q

Define causes & consequences of Neutropenia

A

Causes of neutropenia:

  • B12/ folate deficiency
  • Infiltration of bone marrow by malignancy or fibrosis
  • Aplastic anaemia
  • Radiation- mature cells killed
  • Drugs- chemo, antibiotics
  • Viral infection
  • Congenital disorders

Consequences of neutropenia:

  • Severe life threatening bacterial &/ infection
  • Mucosal ulceration
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6
Q

Definition of monocytes

A

respond to inflammation & antigenic stimuli
migrate to tissues- become macrophages
lysosomes contain lysozyme, complement, interleukins, CSF
phagocytosis, pinocytosis

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7
Q

Causes of monocytosis

A
  • Chronic inflammatory conditions- RA, Crohn’s
  • Chronic infection- TB
  • Carcinoma
  • Myeloproliferative disorders/ leukaemias: CMML; aCML; JMML
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8
Q

Define Eosinophils

A

responsible for dealing with some parasites
mediator of allergic response
migrate to epithelial suraces
phagocytosis of antigen- antibody comple
mediate hypersensitivity reactions- eg to drugs, asthma, skin inflammation

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9
Q

Causes of Eosinophilia

A
  • Allergic diseases: asthma, eczema, hayfever
  • Drug hypersensitivity
  • Hodgkin lymphoma
  • Acute lymphoblastic leukaemia, acute myeloid leukaemia
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10
Q

Define basophils

A

least common but largest
active in allergic reactions & inflammatory conditions
dense granules contain histamine, heparin, hyaluronic acid, serotonin

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11
Q

Causes of Basophilia

A

Reactive: immediate hypersensitivity reactions, UC, RA
Myeloproliferative: CMC, MPN (ET/ PRV/ MF), systemic mastocytosis

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12
Q

Define lymphocytes

A

originate in bone marrow
B cells (humoral immunity)- antibody (immunoglobulin) forming cells
T cells (cellular immunity)- CD4+ helper cells, CD8+ cells
Natural killer cells (cell mediated cytotoxicity)

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13
Q

Causes of lymphocytosis

A

Reactive: viral infections, bacterial infections, stress relted, post splenectomy, smoking
Lymphoproliferative (ie malignant): chronic lymphocytic leukaemia (B cells), T or NK cell leukaemia, lymphoma

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14
Q

Describe the appearance and the function (4) of the spleen

A

• Red pulp- sinuses lined by endothelial macrophages and cords
• White pulp- similar structure to lymphoid follicles
• Blood enters via the splenic artery and white cells and plasma preferentially pass through the white pulp and red cells pass through the red pulp
• Functions:
1. Sequestration and phagocytosis
Old/abnormal RBCs removed by macrophages
2. Blood pooling
Platelets & RBC rapidly mobilised during bleeding
3. Extramedullary Haemopoiesis
4. Immunological function
25% of T cells and 15% of B cells present in the spleen

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15
Q

Define hyposplenism and (3) causes

A 
= lack of functioning splenic tissue
causes:
-	Splenectomy
-	Sickle cell disease 
-	Coeliac disease
Blood film reveal Howell Jolly Bodies
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16
Q

What is the problem If a patient has a lack of functioning spleen tissue?

A
  • Prone to infections by encapsulated bacteria: (-) Neisseria Meningitidis, (+) Streptococcus pneumoniae, (-) Haemophilus influenzae
  • Spleen contains splenic macrophages, T cells and B cells
  • Polysaccharide capsule (sugar) decreases pathogen recognition and adherence by phagocytes
  • Lack of antibody production
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17
Q

Define splenomegaly and (4) causes

A

= enlargement of the spleen; typically associated with an increased workload
causes:
- Haemolytic anaemia: increased number of defective RBS removed from circulation
- Portal hypertension: increases back pressure
- Infiltration by leuaemias and lymphomas

18
Q

What are the clinical signs of splenomegaly

A

• To be able to palpate the spleen below the costal margin
MASSIVE- chronic myeloid leukaemia, myelofibrosis, malaria, schistosomiasis
MODERATE- as above + lymphoma, leukaemia, cirrhosis
MILD- as above + infections, infiltrative disorders, autoimmune diseases

19
Q

Define hypersplenism

A

= low blood count can occur due to pooling of blood in the enlarged spleen
risk of rupture if enlarged and no longer protected by the rib cage- can haemorrhage or outgrow blood supply (infarction)

20
Q

Describe the process of erythropoiesis

A
  • Patient becomes anaemic- reduced pO2 detected in interstitial peritubular cells in kidney
  • Increased production of erythropoietin by the kidney
  • This stimulates maturation and release of RBCs from marrow
  • Total red cells + haemoglobin rises
  • More O2 delivered
  • -ive feedback loop- erythropoietin production falls
21
Q

Explain the concepts of a normal range and be able to assess whether a lab test is likely to be normal or abnormal

A

Range of assays performed in BC will vary slightly from trust to trust including ranges for results

22
Q

Explain the significance of the reticulocyte count

A

Useful test in evaluating different kinds of anaemia

23
Q

Explain the meaning and possible clinical significance of the terms that are frequently used to describe abnormalities in a blood count or film

A

increase= -osis or -ilia

decrease= -enia

24
Q

Display an understanding of how a FBC is analysed

A
  • WBC count
  • RBC count
  • [Haemoglobin]
  • Haematocrit= fraction of whole blood volume that consists of RBCs (average red cell count [mean cell volume] x no .of red cells per litre)
  • Mean cell (/ corpuscular) volume= average volume of red cells measured in femtolitres ( determine whether anaemia is microcytic or macrocytic)
  • Mean cell haemoglobin= [haemoglobin] in a given volume/ no of red cells in same volume
  • Platelet count
  • Reticulocytes
  • Differential WBC counts
  • Blood film/ peripheral blood smear= drop of blood thinly dispersed to obtain monolayer of cells- air dried and fixed in methanol before staining = high/ low counts, blood parasites, abnormalities
25
Q

Define normochromic/ normoncytic

A

no abnormal staining characteristics

normal sized cells

26
Q

Define anisocytosis

A

greater than normal variation in cell size

27
Q

Define poikilocytosis

A

greater than normal variation in shape

28
Q

Define microcytosis

A

presence of abnormally small cells

29
Q

Define macrocytosis

A

presence of abnormally large cells

30
Q

Define hypochromia

A

presence of abnormally pale cells

31
Q

Define elliptocyte

A

RBC elliptical in shape

32
Q

Define ovalocyte

A

RBC oval in shape

33
Q

Define Spherocyte

A

REB sperical in shape (lack central pallor)

34
Q

Define Target Cell (codocyte)

A

RBC where Hb is concentrated at periphery and dot in centre

35
Q

Define Sickle Cell

A

RBC shaped like a sickle (crescent)

36
Q

Define Stomatocyte

A

RBC with slit like stoma

37
Q

Define Schistocyte

A

RBC fragment

38
Q

Defne Acanthocyte (spur cell)

A

RBC with small number of irregular spurs

39
Q

Define Echinocyte (crenated cell)

A

RBC with large number of regular spurs

40
Q

Define Agglutination

A

RBCs forming irregular clumps

MEH (4 decks)

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