Physiology of blood cells Flashcards
what do pluripotent haematopoietic stem cells give rise to?
myeloid stem cells
lymphoid stem cells
what are the key features of stem cells?
self renewal
mature progeny production
what do myeloid stem cells become?
granulocytes
monocytes
erythroid
megakaryocyte
what do lymphoid stem cells become?
T cell
B cell
Natural killer cell
what are the stages of transformation of multipoint myeloid stem cell to erythrocyte?
myeloid stem cell
proerythroblast
erythroblast
erythrocyte
where is erythropoietin produced, and in response to what?
mainly in the kidneys (90%)
in hepatocytes and interstitial cells of liver (10%)
in response to hypoxia
life span of erythrocytes
120 days
where does removal of erythrocytes occur?
in the spleen
Through which cell does transformation of multipoint myeloid stem cell to granulocytes and monocytes take place?
via myeloblast
requires cytokines and interleukins
life span of neutrophil
7-10 hours in circulation before migrating into tissues
function of neutrophils
against infection
lifespan and function of eosinophils
less time spent in circulation than neutrophils
defence against parasitic infection
function of basophils
in allergic response
life span of monocyte
several days in circulation
function of monocytes
become macrophages in tissues
phagocytose
store and release iron
transformation of multipoint haemp. stem cell to platelet
via megakaryocyte
life span of platelet in circulation
10 days
function of platelet
primary haemostasis by
contributing to phospholipid in blood coagulation
circulation of lymphocytes
recirculate into lymph nodes and lymphoid tissues and back into the blood stream
lifespan intervascularly varies a lot
what is the variation in size of cells
anisocytosis
what is the variation in shape of cells
poikilocytosis
what has happened if cells are smaller than normal?
microcytosis
what has happened if cells are larger than normal?
macrocytosis
shapes of macrocytes
round
oval
polychromatic
what are the 3 categories of anaemia?
microcytic- smaller than normal red cells/anaemia with small RBC
normocytic- red cells normal/anaemia with normal RBC
macrocytic- larger than normal red cells/anaemia with large RBC
what causes the large central pallor in RBCs
this region has less Hb and therefore the cell is flatter
what area of the RBC has pallor
third of the diameter
what is hypochromia?
- pallor
increased central pallor
goes hand-in-hand with microcytosis
what are cells like in hyperchromia?
cells are thicker than normal
abnormal shape
lack central pallor
what are the two types of cells in hyperchromia?
1) spherocytes
2) irregular contracted cells
what causes spherocytes to be formed in hyperchromia?
loss of cell membrane without the equivalent loss of cytoplasm forcing the cell to round up
2 disease with characteristic spherocytes?
hereditary spherocytosis
autoimmune haemloytic anaemia
describe irregularly contracted cells
irregular outline
smaller than normal
lack of central pallor
what causes irregularly contracted cells to be formed in hyperchromia?
oxidant damage to cell membrane and Hb
seen in hyposplenism and haemolysis
what does polychromasia describe?
increased blue tinge to cytoplasm of RBC
what does a blue tinge of the cytoplasm of RBC indicate
the RBC is young and often larger in polychromasia
how can you detect young cells in a stain?
blue tinge
reticulocytes stain- using new methylene blue to do a reticulocyte count
the stain in more reliable in diagnosing polychromasia than using the blue tinge
what would you expect the reticulocyte count to be in a normal person?
1-2% of circulation cells should be young reticulocytes
what are the poikilocytes
spherocytes irregularly contracted cells sickle cells target cells elliptocytes fragments
what causes the formation of target cells?
accumulation of Hb in the centre of the central pallor area
in which diseases do target cells occur
obstructive jaundice
liver disease
haemoglobinopathies
hyposplenism (lack of spleen function, due to removal)
which diseases do elliptocytes occur?
hereditary elliptocytosis
iron deficiency
what causes sickle cells to form?
polymerisation of Hb S chains when present at a high enough concentration
what does the presence of fragments indicate?
that a RBC has fragmented due to abnormal stress to the cell or if the cell has been intrinsically abnormal in the first place
what are the 2 ways poikilocytes clump together?
rouleaux- neat stack of RBCs
agglutinates- irregular clumps of RBCs
what causes a rouleaux to form?
alterations in plasma proteins
what causes agglutinates to form?
antibodies attaching to RBC antigens
what can a lack of splenic function also cause to appear commonly?
a Howell-Jolly Body
- nuclear remnant of RBC
“too many”
- cytosis and -philia
e. g. leucocytosis, neutrophilic , eosinophilia, lymphocytosis
“too few”
- penia
e. g. leucopenia, neutropenia
what describes an increase in non-segmented neutrophils?
left shift
- presence of neutrophil precursors in the blood
- band form
[the transformation goes backwards, to the left]
what is toxic granulation?
heavy granulation of neutrophils as a result of infection, inflammation and tissue necrosis
also normal in pregnancy
what do you see in right shift?
hypersegemented neutrophils
increase in average number of neutrophil lobes
caused by lack of vitamin B12 or folic acid (e.g. in megaloblastic anaemia where DNA synthesis has been inhibited)
