Physiology of Blood Cells and Haematological Terminology Flashcards
What are all blood cells ultimate derived from?
Pluripotent haematopoietic stem cells
What two lineages can this give rise to?
Lymphoid
Myeloid
What cells are derived from the multipotent myeloid precursor?
Megakaryocytes
Granulocyte-Monocyte
Erythroid
What cells are derived from the multipotent lymphoid precursor?
T cells
B cells
NK cells
What are some common features of blasts?
They have a large nucleus and a small amount of cytoplasm
How does the colour of red cells change as they mature?
When they are immature they are 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 the juxtatubular interstitial cells It is also 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?
As they lack a nucleus, red blood cells have an extensive cytoskeleton meaning that it is very flexible and can fit through small gaps
As the cells get older, they becomes less flexible and less able to pass through the capillaries into the sinuses in the spleen
This means that they are more likely to be retained in the spleen and 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.
The red cells have a larger area of central pallor than normal
NOTE: normal red cells have a central pallor that covers around 1/3 of the red cell diameter
NOTE: hypochromia and microcytosis tend to go together
Define hyperchromia.
The red cells lack a central pallor
State two important types of hyperchromatic cells.
Spherocytes
Irregularly Contracted Cells
What is responsible for the round shape of the spherocytes in spherocytosis?
It is caused by a loss of cell membrane that is not accompanied by an equivalent loss of cytoplasm
State a cause of spherocytosis.
Hereditary spherocytosis
What usually causes the formation of irregularly contracted cells?
Oxidant damage
Define polychromasia.
An increased blue tinge to the cytoplasm of a cell
What can reticulocytes be stained with?
Methylene blue
State six different types of poikilocytosis.
Spherocytes Elliptocytes Fragments Irregularly contracted cells Target cells Sickle cells
What are target cells? State some causes of target cells in the blood film.
Target cells have an accumulation of haemoglobin in the middle of the central pallor
It is caused by obstructive jaundice, hyposplenism, liver disease, haemoglobinopathies
State two causes of eliptocytosis.
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?
Schistocytes
