Physiology of Blood Cells and Haematological Terminology Flashcards
(49 cards)
What are all blood cells ultimate derived from?
Multipotent haematopoietic stem cells
What 2 lineages can multipoint stem cells give rise to?
Lymphoid stem cells
Myeloid stem cells
What 3 cells are derived from the multipotent myeloid precursor?
Megakaryocytes
Granulocyte-Monocyte
Erythroid
What 3 cells are derived from the multipotent lymphoid precursor?
T cells
B cells
NK cells
What are 2 common features of blasts?
Large nucleus
Small amount of cytoplasm
How does the colour of red cells change as they mature?
Immature= more blue/purple
As they mature they become pinker
Which cells produce EPO? What can trigger the production of EPO?
EPO is mainly produced in the kidneys by juxtatubular interstitial cells
Produced to a lesser extent by the liver
EPO production is stimulated by hypoxia
What is the life span of a red blood cell?
120 days
What feature allows red blood cells to wriggle through small holes in the capillaries in the spleen?
Lack a nucleus
Have an extensive cytoskeleton so are very flexible + can fit through small gaps
On ageing becomes less flexible + less able to pass through capillaries into sinuses in the spleen
Thus are more likely to be retained in the spleen + phagocytosed
Define anisocytosis and poikilocytosis
Anisocytosis = red cells show more variation in SIZE than is normal Poikilocytosis = red cells show more variation in SHAPE than is normal
What can be used as a reference in a blood film to determine whether the red blood cells are microcytic or macrocytic?
Lymphocytes are generally all the same size
Define hypochromia. What does it result from and what is it often seen in conjunction with?
Red cells have a larger area of central pallor than normal
(normal central pallor covers ~1/3 of red cell diameter)
Results from a lower Hb content + concentration + a flatter cell
Hypochromia + microcytosis tend to go together
Define hyperchromia. What can this result from?
Red cells lack central pallor.
Can occur because they are thicker than normal or because their shape is abnormal
State 2 important types of hyperchromatic cells.
Spherocytes
Irregularly Contracted Cells
What is responsible for the round shape of the spherocytes in spherocytosis?
Loss of cell membrane that is not accompanied by an equivalent loss of cytoplasm
Cell is forced to “round up”
State a cause of spherocytosis.
Hereditary spherocytosis
What usually causes the formation of irregularly contracted cells?
Oxidant damage to the cell membrane + Hb
Define polychromasia.
An increased blue tinge to the cytoplasm of a cell
Indicates that the red cell is young.
What can reticulocytes be stained with?
Methylene blue.
Precipitates as a network (reticulum)
State 6 different types of poikilocytosis.
Spherocytes Elliptocytes Fragments Irregularly contracted cells Target cells Sickle cells
What are target cells? State 4 causes of target cells in the blood film.
Have an accumulation of Hb in the middle of the central pallor
Occur in obstructive jaundice, hyposplenism, liver disease, haemoglobinopathies
Describe elliptocytes. State 2 causes of eliptocytosis.
Elliptical in shape
Hereditary eliptocytosis
Iron deficiency (also hypochromic)
What biochemical phenomenon causes the sickling of red blood cells?
Polymerisation of haemoglobin S when present in a high concentration
What is another name for fragments? What do fragments indicate?
Schistocytes
Indicate a red cell has fragmented
