Physiology of Blood Cells and Haematological Terminology Flashcards
What are all blood cells ultimate derived from?
multipotent haematopoietic stem cells
What two lineages can this give rise to?
Lymphoid Stem Cells
Myeloid Stem Cells
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
Multipotent haematopoietic stem cells give rise to blasts eg myeloblast
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
– blue tinge to cytoplasm– young POLYCHORMASIA
What is EPO used for?Which cells produce EPO? What can trigger the production of EPO?
Erythropoiesis
EPO is mainly produced in the kidneys by the juxtatubular interstitial cells (90%)
10% liver– heaptocyte and interstitial cells
EPO production is stimulated by hypoxia or anaemia
What is the life span of a red blood cell? What is it destroyed by?
120 days
Phagocytic cells of spleen
Define anisocytosis and poikilocytosis
Anisocytosis = red cells show more variation in SIZE than is normal (latin for aniso= uneven) Poikilocytosis = red cells show more variation in SHAPE than is normal (poikilo=variation/uneven)
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 and are used as a reference.
Normally RBCs are a bit smaller than lymphocytes
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 as they are both caused by reduced Hb synthesis
Define hyperchromia.
The red cells lack a central pallor– normal rbc have a pale centre
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 (inadequate attachment between cytoskeleton and membrane)
State a cause of spherocytosis.
Hereditary spherocytosis– but not all the cells are spherical
How do irregularly contracted cells differe in appearance from normal rbc? What usually causes the formation of irregularly contracted cells?
Irregulat in outline, smaller and no central pallor
Oxidant damage
Define polychromasia.
An increased blue tinge to the cytoplasm of a cell– INDICATES CELL IS YOUNG
What can reticulocytes (IMMATURE RBC) 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
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
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)
Which cytokines are important in the for the process of multipotent haemopoietic stem cell –> myeloblast+monoblast
monoblast–> granulocytes and monocytes
G-CSF granulocyte colony stimulating factor
M-CSF macrophage CSF
GM-CSF granulocyt-macrophage csf
Interleukins
How long do neutrophils survive for in the circulation?
7-10 hours
What is the main role of eosinophils?
eosinophil granulocytes arise from what?
Parasitic infections.
Myeloblast
Describe the shape of the nucleus of an eosinophil.
Time in circulation compared to neutrophil
Eosinophils have a bilobed nucleus
less time in circulation than neutrophil
What is the main role of basophils?
Basophil granulocytes arise form
They are involve in the allergic response, histamine release etc
Myeloblast
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
Describe the appearance of monocytes.
Arise from
Time spent in circulation
They have a kidney bean shaped nucleus
They are large
Myeoloid stem cells–> Monoblasts–> promonocytes–> monocytes
SevERL DAYS
Other than phagocytosis, what is another role of macrophages? apart from differentiating into macrophages they also differentiate into?
They store and release iron
histiocytes
How long do platelets survive for in the circulation?
Arise from
Role of platelets
10 days
Haematopoietic stem cells
primary haemostasis and contribute phospholipid which promotes blood coagulation
What term is used to describe having too many white blood cells?
Leucocytosis
What term is used to describe having too many platelets?
Thrombocytosis
Describe the appearance of an atypical lymphocyte. What can cause these to appear in a blood film?
An atypical lymphocyte will have a large nucleus and a large amount of faint cytoplasm
This is typical of having a viral infection and is seen in glandular fever (infectious mononucleosis)
What is toxic granulation? What can cause it?
This is the heavy granulation of neutrophils
It results from infection, inflammation and tissue necrosis
It is also a feature of normal pregnancy
What is hypersegmentation of neutrophils? What can cause it?
Neutrophil hypersegmentation means that there is an increase in the average number of neutrophil lobes or segments (normal= 3 or 4 lobes)
It usually results from a lack of vitamin B12 or folic acid
Macrocyte and microcytes are
Red blood cells
Different types of macrocytes
Round
Oval– Significant vit b12/ folic acid deficiency
Polychromatic macrocytes– lots of young cells in circulation
What is a left shift
Left shift means that there is an increase in non-segmented neutrophils or that there are neutrophil precursors in the blood
Neutrophil goes back to looking more like monoblasts
Essential stem cell characteristics
Ability to self-renew and produce mature progeny
Ability to divide into two cells with different characteristics, one another stem cell and the other a cell capable of differentiating to mature progeny
How do rbc arise
The myeloid stem cell/precursor can give rise to a proerythroblast
This in turn gives rise to erythroblasts and then erythrocytes
size difference between reticulocytes and rbc
Reticulocytes are larger
Leucocytosis
Too many white cells
Leucopenia
too few white cells
Neutrophilia
Too many neutrophils
Neutropenia
Too little neutropils
Lymphocytosis
Too many lymphocytes
Atypical lymphocyte
Abnormal lymphocyte
Often the term is used to describe the abnormal cells present in infectious mononucleosis (‘glandular fever’)
‘Atypical mononuclear cell’ is an alternative term
