Physiology of Blood Cells and Haematological Terminology Flashcards

1
Q

Outline the stem cell heirarchy

A

pluritpotent lympphoid-myeloid stem cell ->lymphoid stem cell/ multipotent myeloid stem cell or precursor

lymphoid sc-> t cell/ b cell/ nk cell

myeloid sc-> granulocyte-monocyte/erythroid/magakarocyte

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2
Q

outline normal erythroid maturation

A

multipotent myeloid sc-> proerythroblast -> early,intermediate and late erythroblats-> erythrocyte

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3
Q

What stmulates erythropoiesis? Where does it occur?

A

hypoxia/anaemia

90% of erythropoietin from juxtatubular interstitial cells of the kidneys.

10% of erythropoietin from hepatocytes and interstitial cells of the liver

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4
Q

How long do erythrocytes survive?

A

about 120 days in the blood stream and transport CO2 and O2 -> then destroyed by phagocytes in spleen

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5
Q

outline the normal granulocyte maturation?

A

multipotent myeloid sc-> myeloblast -> promyelocyte-> myelocyte-> band form -> neutrophil

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6
Q

What is the physiological function of neutrophils?

A

Neutrophil granulocyte survives 7-10 hours in circulation before migrating to tissues.

Defence against infection - phagocytoses and then kills microorganisms

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7
Q

What is the physiological function of eosinophils?

A

Spends less time in circulation than neutrophil.

Defence against parasitic infection

also involved in allergic reactions

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8
Q

What is the physiological function of basophils?

A

allergic responses

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9
Q

What is the physiological function of monocytes?

A

Spend several days in the circulation.

Phagocytose bacteria, fungi and dead tissue.

Migrate to tissues to become macrophages.

Macrophages store and release iron

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10
Q

What is the physiological function of platelets?

A

Multipotent haematopoietic stem cell -> megakaryocyte -> platelet.

Survive 10 days in circulation.

Have a role in primary haemostasis in contributing phospholipid to promote blood coagulation

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11
Q

What is the physiological function of lymphocytes?

A

Lymphoid stem cell gives rise to T, B and NK cells.

Lymphocytes recirculate to lymph nodes and other tissues and then back into the blood stream.

Lifespan intravascular is very variable

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12
Q

What do anisocytosis and poikilocytosis mean?

A

Anisocytosis – red cells show more variation in size than is normal

Poikilocytosis – more variation in shape than is normal

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13
Q

What do microcytosis and macrocytosis mean?

A

Microcytosis – red cells smaller than normal.

Macrocytosis – larger than normal.

types of macrocytes :
Round macrocytes.
Oval macrocytes.
Polychromatic macrocytes (darker blue due to ribosomes -> newly synthesized)

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14
Q

What arethe categories of anaemia?

A

Microcytic – red cells that are smaller than normal or an anaemia with small red cells.

Normocytic – red cells of normal size or an anaemia with normal sized red cells.

Macrocytic – red cells that are larger than normal or an anaemia with large red cells

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15
Q

What is hypochromia?

A

RBCs that have a large central pallor – less haemoglobin in the cell and thus a flatter cell and less colour

Normal RBCs have one-third a diameter that is pale.

*Often Hypochromia and Microcytosis go hand-in-hand - both caused by reduced haemoglobin

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16
Q

What is hyperchromia?

A

The cells LACK central pallor – the cells are thicker than normal or have an abnormal shape.

There are 2 important types of cell in Hyperchromia;

  1. Spherocytes
    - These are approximately spherical in shape and so lack central pallor.
  • They result from the loss of cell membrane without the equivalent loss of cytoplasm so the cell is forced to round up - One such disease of these – Hereditary spherocytosis.
  1. Irregularly contracted cells – top picture.
    - Irregular in outline but smaller than normal cells and have lost central pallor.
  • A result of oxidant damage to the cell membrane and haemoglobin
17
Q

What is polychromassia?

A

Describes an increased blue tinge to the cytoplasm of a red cell.

This indicates the cell is young and is often much larger.

Another way to detect young cells like these is in a “reticulocyte stain” which exposes living red cells to NMB (New Methylene Blue) which precipitates the network seen inside the cell.

Should only have 1-2% of these cells in the population circulating.

Identifying these is more reliable than looking for Polychromasia on a slide so you should do this to diagnose Polychromasia

18
Q

What are the different types of poikocytes?

A

spherocytes

irregularly contracted cells

Target Cells

Elliptocytes

Sickle cells

Fragments/Shistocytes

19
Q

What causes sickle cell?

A

result from polymerisation of haemoglobin S chains when present at a high enough concentration

20
Q

What causes shistocytes?

A

small pieces of red cells indicating a cell has fragmented

Can be due to abnormal stress on the red cell or from if the cell is intrinsically abnormal

21
Q

What are target cells?

A

cells with an accumulation of haemoglobin in the centre of the area of central pallo

Occur in obstructive jaundice, liver disease, Haemoglobinopathies and hyposplenism.

22
Q

What are ellipocytes?

A

elliptcal in shape

Occur in hereditary elliptocytosis and in iron deficiency.

23
Q

What is rouleaux formation?

A

STACKS of red cells.

Result from alterations in plasma proteins.

*like a stack of coins

24
Q

What are agglutinates?

A

irregular clumps of red blood cells.

Result of antibodies on the surface of the cells

*like an untidy pile of coins

25
Q

What is a Howell-Jolly body?

A

a nuclear remnant in a red cell.

Commonest cause is a lack of splenic function

26
Q

What is leucocytosis and leucopenia

A

Leucocytosis - too many white cells.

Leucopenia – too few white cells.

27
Q

What is neutrophilia and neutropenia?

What are the words for too many lymphocytes and too many eosinophils?

A

Neutrophilia – too many neutrophils.

Neutropenia – too few neutrophils

lymphoctyosis and eosinophilia

28
Q

What is left shift?

A

describes the increase in non-segmented neutrophils or that there are neutrophil precursors in the blood.

So there would be more non-segmented neutrophils in the plasma (otherwise known as “band form”)

29
Q

What is toxic granulation?

A

heavy granulation of neutrophils.

A result of infection, inflammation and tissue necrosis (but also normal in pregnancy)

30
Q

What is hypersegmentation of neutrophils?

A

means there is an increase in the average number of neutrophil lobes or segments.

It is usually a result of lack of vitamin B12 or folic acid

31
Q

Why is there more space between blood cells in anaemic patients?

A

blood is less viscous so when you place it on a slide it spreads more thinly

32
Q

How does sickle cell lead to Howell jolly bodies?

A

occlusion of blood vessels in spleen -> infarction of spleen -> subsequent loss of splenic function