Physiology of Blood Cells and Haematological Terminology Flashcards
Outline the stem cell heirarchy
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
outline normal erythroid maturation
multipotent myeloid sc-> proerythroblast -> early,intermediate and late erythroblats-> erythrocyte
What stmulates erythropoiesis? Where does it occur?
hypoxia/anaemia
90% of erythropoietin from juxtatubular interstitial cells of the kidneys.
10% of erythropoietin from hepatocytes and interstitial cells of the liver
How long do erythrocytes survive?
about 120 days in the blood stream and transport CO2 and O2 -> then destroyed by phagocytes in spleen
outline the normal granulocyte maturation?
multipotent myeloid sc-> myeloblast -> promyelocyte-> myelocyte-> band form -> neutrophil
What is the physiological function of neutrophils?
Neutrophil granulocyte survives 7-10 hours in circulation before migrating to tissues.
Defence against infection - phagocytoses and then kills microorganisms
What is the physiological function of eosinophils?
Spends less time in circulation than neutrophil.
Defence against parasitic infection
also involved in allergic reactions
What is the physiological function of basophils?
allergic responses
What is the physiological function of monocytes?
Spend several days in the circulation.
Phagocytose bacteria, fungi and dead tissue.
Migrate to tissues to become macrophages.
Macrophages store and release iron
What is the physiological function of platelets?
Multipotent haematopoietic stem cell -> megakaryocyte -> platelet.
Survive 10 days in circulation.
Have a role in primary haemostasis in contributing phospholipid to promote blood coagulation
What is the physiological function of lymphocytes?
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
What do anisocytosis and poikilocytosis mean?
Anisocytosis – red cells show more variation in size than is normal
Poikilocytosis – more variation in shape than is normal
What do microcytosis and macrocytosis mean?
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)
What arethe categories of anaemia?
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
What is hypochromia?
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
What is hyperchromia?
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;
- 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.
- 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
What is polychromassia?
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
What are the different types of poikocytes?
spherocytes
irregularly contracted cells
Target Cells
Elliptocytes
Sickle cells
Fragments/Shistocytes
What causes sickle cell?
result from polymerisation of haemoglobin S chains when present at a high enough concentration
What causes shistocytes?
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
What are target cells?
cells with an accumulation of haemoglobin in the centre of the area of central pallo
Occur in obstructive jaundice, liver disease, Haemoglobinopathies and hyposplenism.
What are ellipocytes?
elliptcal in shape
Occur in hereditary elliptocytosis and in iron deficiency.
What is rouleaux formation?
STACKS of red cells.
Result from alterations in plasma proteins.
*like a stack of coins
What are agglutinates?
irregular clumps of red blood cells.
Result of antibodies on the surface of the cells
*like an untidy pile of coins
