Physiology of Blood Cells and Haematological Terminology Flashcards
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
State 2 different ways in which red blood cells can clump together and describe why they happen.
Rouleaux: like a stack of coins – caused by a change in plasma proteins pushing the red cells together, common in infection/ inflammation
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?
A nuclear remnant in the red cells
Commenest cause= a lack of splenic function (spleen should remove these tiny bits of nuclear material)
Which cytokines are important in the differentiation of myeloblasts to granulocytes and monocytes?
G-CSF
M-CSF
GM-CSF
Interleukins
How long do neutrophils survive for in the circulation?
7-10 hours
What is the main role of eosinophils?
Defence against Parasitic infections
Describe the shape of the nucleus of an eosinophil.
Eosinophils have a bilobed nucleus
What is the main role of basophils?
Involved in allergic response
Describe the appearance of basophils.
Many dark blue dots in the cytoplasm (granules)
Often, so many that you can’t see the nucleus
Describe the appearance of monocytes.
Kidney bean shaped nucleus
Large
Other than phagocytosis and scavenging, state a role of macrophages
Store + release iron
How long do platelets survive for in the circulation?
10 days
What term is used to describe having too many and too few white blood cells?
Excess: Leucocytosis
Deficient: Leucopenia
What term is used to describe having too many and too few platelets?
Excess: Thrombocytosis
Deficient: Thrombocytopenia
Describe the appearance of an atypical lymphocyte. What can cause these to appear in a blood film?
Large nucleus + a large amount of faint cytoplasm
Often seen in glandular fever (infectious mononucleosis)
What is ‘left shift’?
An increase in no. of non-segmented neutrophils or that there are a lot of neutrophil precursors in the blood
E.g. presence of many neutrophils with band form nuclei
What is toxic granulation? What can cause it?
Heavy granulation of neutrophils
Results from infection, inflammation + tissue necrosis
A feature of normal pregnancy
What is hypersegmentation of neutrophils? What can cause it?
An increase in the average number of neutrophil lobes or segments (>6)
Results from a lack of Vitamin B12 or folic acid
What are the 2 essential characteristics of stem cells?
Ability to self renew
Ability to produce mature progeny
What is the main function of a neutrophil?
Defence against infection- phagocytoses + kills micro-organisms
What are the main roles of platelets?
Role in primary haemostasis
Contribute phospholipid, which promotes blood coagulation
Describe the life of lymphocytes
Recirculate to lymph nodes + other tissues + back into blood stream
Life span very variable
List 3 types of macrocyte
Round macrocytes
Oval macrocytes (common in B12 + folic acid deficiency)
Polychromatic macrocytes
Define microcytic, normocytic and macrocytic
Micro: Red cells smaller than normal or an anaemia with small red cells
Normo: Red cells of normal size or an anaemia with normal sized red cells
Macro: Red cells larger than normal or an anaemia with large red cells
What term is used to describe having too many and too few neutrophils?
Excess: Neutrophilia
Deficient: Neutropenia
What term is used to describe having too many and too few lymphocytes?
Excess: Lymphocytosis
Deficient: Lymphopenia
