Red Cells and Haemolysis Flashcards
what is haemopoesis?
ther production of blood cells
what are the sites of haematopoiesis from embryo to adulthood?
embryo- yolksac
birth- mostly bone marrow, liver
adult- bone marrow of axial skeleton
what is an erythrocyte?
mature red cell (doesn’nt have a nucleus)
what are mature red cells first called?
reticulocytes
(due to rRNA meshwork that can be seen under microscopy)
what cells are described as polymorph (segmented nucleus)?
neutrophils
what can cause an increase in neutrophils?
body stress- infection, trauma, infarction
what blasts are often elevated in people with allergies i.e. asthma/dermatitis?
eosinophils
how do eosinophils appear under microscope?
bi-lobed
bright red/orange granules
how do basophils stain under microscope?
large deep purple granules
what do basophil granules contain?
histamine
what is the production of red blood cells called?
erythropoesis
what regulates the poduction of red blood cells?
erythropoietin
where is erythropoietin released?
kidneys
what role do the kidneys play n eryhtropoeisis?
hypoxia sensed by kidney which then releases erythropoetin stimulating erythropoeisis
haemoglobin is what kind of protein?
tetrameric globular protein
- 2 alpha
- 2 beta
what is the haen group in haemoglobin?
porphyrin ring
where does red cell desrtuction usually take place?
in the spleen- red cells taken up by macrophages and contents recycled
what are the contents of red blood cells recycled to?
globin → amino acids
heam group → iron and bilirubin
what happens to the bilirubin formed from the breakdown of red cells?
binds to serum albumin and trasnferred to liver to become conjugated and is then excreted in urine and faeces
how is carbon dioxde transported in the blood?
10% dissolved in soln
30% bound directly to Hb
60% as bicarbonate
what is the shape of the oxygen dissociation curve?
sigmoidal
as one oxygen binds, on eunit changes its shape and the ability of oxygen to bind to the next unit. what is this called?
allosteric effect
what happens to oxygen delivery if the curve is shifted to the right?
more oxygen delivered to the tissues
what is the structure of fetal haemoglobin?
2 alpha chains and 2 gamma chains- HbF
can feotal hameoglobin take oxygen from maternal curculation?
yes- diff shape means diff curve: if mums blood in placenta is 80% saturation foetal will be 90%
why are red cells more susceptible ot damage?
biconcave shape
no mitochondria
no nucleus
why is the lack of mitochondria and nucleus significant in red cells with regards to damage?
they have a limited metabolic reserve
can’t generate new proteins
what is compensated hameolysis?
inc in red cell production to compensate for inc in red cell destruction
what is decompensated haemolysis?
inc rate of red cell destruction exceeding bone marrow capacity for red cell production
Hb falls
what is another name for decompnesated hameolysis?
haemolytic anaemia
what is the bone marrow response to haemolysis?
reticulocytosis
erythroid hyperplasia
which is more common extravascular or intravascular red cell desruction?
extravascular- at site of destruciton
what happens in extravascular hameolysis?
release of protoporphyrin leading to escess unconjugated bilirubin
what happens in intravascular haemolysis?
red cells destroyed in circulation spilling contents
what are some causes of intravascular haemolysis?
ABO incompatible blood transfusion
G6PD deficiency
severe falciparum malaria (blackwater fever)
ho wdo you investigate haemolysis?
FBC/film
reticulocyte count
serum unconjugated bilirubin
coombs test
what is the purpose of coombs test?
tests for antibodies againt RBC
what does membrane damage indicate on blood film?
spherocytes
how is mechanical damage indicated on blood film?
red cell fragments
how is oxidative damage indicated on blood film?
heinz bodies
what immunoglobulin is seen in warm autoimmune haemolysis?
IgG
what are causes of warm (igG) autoimmune haemolysis?
idiopathic
autoimmune disorders (SLE)
drugs (peniclllins)
infections
what immunoglobulin is seen in cold autoimmune haemolysis?
IgM
what are some causes of cold (IgM) autoimmune haemolysis?
idiopathic
infections (EBV, mycoplasma)
lymphoproliferative disorders
other than autoimmune haemolyisis what other form of immune haemolysis is there?
Alloimmune haemolysis
what can cause alloimmune haemolysis?
immune response
passive transfer of antibody- Haemolytic disease of newborn
what are some mechanical causes of haemolysis?
Disseminated Intravascular Coagulation (DIC)
HUS (E.Coli 0157)
Leakign heart valve
infections i.e malaria
what is the only type of haemolysis to show microspherocytes on blood film?
burns related haemolysis- red cells sheared as they pass through damaged capillaries
