Physiology of Blood Cells and Haematological Terminology Flashcards
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
What does polychromasia indicate about the cell
It is young
Causes of target cells
It is caused by obstructive jaundice, hyposplenism, liver disease, haemoglobinopathies
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 usually causes the formation of irregularly contracted cells?
Oxidant damage
What is another name for fragments?
Schistocytes
Define polychromasia.
An increased blue tinge to the cytoplasm of a cell
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
State six different types of poikilocytosis.
Spherocytes Elliptocytes Fragments Irregularly contracted cells Target cells Sickle cells
What cells are derived from the multipotent myeloid precursor?
Megakaryocytes
Granulocyte-Monocyte
Erythroid
State two important types of hyperchromatic cells.
Spherocytes
Irregularly Contracted Cells
How long do platelets survive for in the circulation?
10 days
What are target cells?
Target cells have an accumulation of haemoglobin in the middle of the central pallor
State a cause of spherocytosis.
Hereditary spherocytosis
State two different ways in which red blood cells can clump together and describe why they happen.
Rouleaux – like a stack of coins – it is caused by a change in plasma proteins pushing the red cells together
Agglutinates – irregular clumps – caused by antibodies on the cell surface making the cells stick together
Describe the appearance of basophils.
They have lots of dark blue dots in the cytoplasm (granules)
Often there are so many blue dots that you can’t even see the nucleus
What biochemical phenomenon causes the sickling of red blood cells?
Polymerisation of haemoglobin S when present in a high concentration
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
What are all blood cells ultimate derived from?
Pluripotent haematopoietic stem cells
What is the main role of basophils?
They are involve in the allergic response
Describe the shape of the nucleus of an eosinophil.
Eosinophils have a bilobed nucleus
How long do neutrophils survive for in the circulation?
7-10 hours
What are some common features of blasts?
They have a large nucleus and a small amount of cytoplasm
What cells are derived from the multipotent lymphoid precursor?
T cells
B cells
NK cells
3 features of irregularly contracted cells
Irregular in outline
Smaller than normal
Lost their pallor
Other than phagocytosis, what is another role of macrophages?
They store and release iron
State two causes of eliptocytosis.
Hereditary eliptocytosis Iron deficiency (also hypochromic)
What is the life span of a red blood cell?
120 days
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
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 and anaemia
Describe the appearance of monocytes.
They have a kidney bean shaped nucleus
They are large
What can reticulocytes be stained with?
Methylene blue
What two lineages can this give rise to?
Lymphoid
Myeloid
Define hyperchromia.
The red cells lack a central pallor
What is a Howell-Jolly Body and what is it usually caused by?
This is a nuclear remnant in the red cells
This is most commonly caused by a lack of splenic function (the spleen should remove these tiny bits of nuclear material)
What is the main role of eosinophils?
Parasitic infections
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
