physiology of blood cells and haematological terminology Flashcards
summarise the physiology of all blood cells *
origenate in bone marrow
derived form multipotent haemopoetic stem cells
they give rise to lymphoid and myeloid stem cells
myeloid goive rise to - granulocyte (monocyte), erythroid, megakaryocyte
lymphpoid - T B and NK cell
what are the essential characteristics of stem cells
abiliuty to self renew
ability to make new mature progeny
describe the origen of RBC *
myeloid stem cell give rise to 2 proerythroblasts (earliest RBC)
gives rise to 2 erythroblasts (has nucleus)
gives rise to early, intermediate and late erythroblasts
give rise to 2 erythrocytes (lost nucleus) - the cytoplasm is squezed through the endothelium to the sinusoid, leaving nucleus to be ingested by macrophage
this process is erythropoesis
what is needed for erythropoesis and what stimulates it *
erythorpoeitin
stimulated by hypoxia
90% synthesised in the kidney by juxtatubular interstitial cell, 10% synthesised by hepatocytes and interstitial cells in liver - all pass into capillaries and enter marrow through blood
increased erythropoetin = increased bone marrow activity = increased red cell production
what is the intravascular life span of erythrocytes *
120 days
ultimately destroyed by the phagocytic cells (macrophages) of the spleen and liver and reticuloendothelial system
what is the function of RBC *
main - O2 transport
some CO2 transport (mainly in plasma though)
nitric oxide transport
Hb acts as buffer
describe the origen of WBC *
myeloblast -> granulocyte and monocytes
chromatin gets more condensed and nucleus gets indented
cytokines influence the pathwya of stem cells
granulocyte colonly stim factor, macrophage - CSF, granulocyte macrophage CSF and inbterleukins stim the granulocyte and monocyte pathway
describe polychromatic erythrocytes *
they are in circulation
larger and have ribosomes in cytoplasm that control Hb synth
how can you see if there are young red cells
reticulocyte stain - reticulocytes take up methylene blue and it pptes into reticulum/network
or stain normal film see if there are any blue/larger cells
detecting reticulocytes is more reliable
what is the lifespan of a neutrophil *
7-10 hrs in circulation before entering tissues
function of neutrophil*
defence against infection - phagocytosis
2 pools:
circulating - flows down blood stream
marginating - adherent to endothelium, start to enter tissues - enter by diapedesis then chemotaxis in tissue under influence of chemokines
what is the origen of eosinophils *
myeloblast
what is the life span of an eosinophil *
less than neutrophil
function of eosinophil *
fight paracytic infection by releasing granule contents
describ ethe origin of basophils *
myeloblasts
describe the function of basophils *
allergic responses - infective and inflammatory aspects
describe the lifespan of monocytes *
several days in the circulation then migrate into tissues - become monlyctes
function of macrophages *
phagocytic and scavenging
they take up erythrocytes that die, break down ferritin store as haemosiderin - provides a store of iron in the bone marrow when needed
what is the lifespan for a platelet *
10 days in circulation
describe the origin of platelets *
fragmentation of the cytoplasm of megakaryocytes
leave the nucleus in marrow to be destroyed
they are under the influence of thrombopoietin
what is the function of platelets *
primary haemostasis
contribute phospholipid which promotes blood coagulation
what is the life span for lymphocytes *
variable
they recirculate between the blood, lymph nodes and other tissues so provide host defence across whole body
define anisocytosis *
RBC show more variation in size than is normal
define poikilocytosis *
RBC show more variation in shape than is normal
define microcytosis *
RBC smaller than normal
define macrocytosis *
red cells are larger than normal
how do you identify the size of red cells
compare diamter with nucleus of leukocytes - should be similar
or use automated size counters
what is a microcyte *
a red cell that is smaller than normal
what is a macrocyte *
a red cell that is larger than normal
describe the different types of macrocytes *
depend on shape and staining characteristics
- round macrocytes
- oval macrocytes - indicative of B12 or folic acid deficiency
- polychromatic macrocytes - young cell, present in response to heamorrage or administration of a vitamin that was lacking
define microcytic *
desribes red cells that are smaller than normal, or an anaemia with small red cells
define normocytic *
describes red cells that are of normal size or an anaemia with normal sized red cells
describe macrocytic *
describes red cells that are larger than normal, or an anaemia with larger than normal red cells
desribe hypochromia in comparison to normal red cells *
normal red cells have 1/3 diameter pale - because of disk shape centre has less Hb than edge therefore paler - this is central pallor
in hypochromia - larger than normal central pallor - because of low Hb content, conc and a flatter cell - red cells are hypochromic
hypochromia and microcytosis go together (same underlying condition eg Fe deficiency or thalassaemia)
describe hyperchromia *
cells lack central pallor
because they are thicker (macrocytes) or because shape is abnormal
cells are called hyperchromatic/hyperchromic
2 main causes of hyperchromia *
spherocytes (round outline)
and irregularly contracted cells (Hb all in 1 place)
cause of spherocytes *
hereditory spherocytosis - membrane not tethered to the cytoskeleton so lose membrane
loss of membrane w/o loss of equivalent amount of cytoplasm - so cell is forced to round up to enclose cytoplasm in remaining membrane
describe irregularly contracted cells *
irregular outline
smaller than normal
lost central pallor
because of oxidant damage to the membrane and Hb because of foreign chemical or food eg broad beans - if dont have normal enzymes this causes haemolytic anaemia
describe polychromasia *
blue tinge to red cell cytoplasm - mean cell is young
descirbe the different shapes of poikilocytes *
spherocytes
irregularly contracted cells
sickle cells
target cells - blob of Hb in central pallor
elliptocytes
fragments- angular
the causes of target cells *
obstructive jaundice
liver disease
haemoglobinopathies
hyposplenism
causes of elliptocytes *
hereditory elliptocytosis
iron deficiency
cause of sickle cells *
HbS polymerisation when present in high conc
describe boat cells *
some polymerisation of HbS - not enough to form sickle
describe fragments *
also called schistocytes
small pieces of red cells
indicate that a cell has fragmented
describe rouleaux *
stacks of red cells
resemble a pile of coins
result from alterations in plasma proteins eg increase in Ig (M - big molecular weight) mean neutralising force is negated = stack
normally red cells repel each other
describe agglutins *
irregular clumps of red cells
because of Ab on surface of red cells cause them to stick together
what is a Howell-Jolly body and what is the cause *
a nuclear remnant in a red cell
commonest cause - lack of splenic func eg atrophy
define leucocytosis *
too many white cells
define leucopinea *
too few white cells
define neutrophilia *
too many neutrophils
define neutropenia *
too few neutrophils
define lymphocytosis *
too many lymphocytes
describe eosinophilia *
too many eosinophils
define thrombocytosis *
too many platelets
define thrombocytopenia *
too few platelets
define erythrocytosis *
too many RBC
define reticulocytosis *
too many reticulocyts
define lymphopenia *
too few lymphocytes
what is an atypical lymphocyte *
describes the abnormal cells present in infectious mononucleosis - glandular fever
atypicalk mononuclear cell is anotehr term
summarise left shift *
there is an increase in non-segmented neutrophils or that there are neutrophil precursers in the blood
sign of infection/inflammatiom
summarise R shift *
increase in segments or lobules in nucleus of neutrophils
describe toxic granulation *
heavy granulation of neutrophils
from infection, inflammation and tissue necrosis
normal feature of preg
describe hypersegmented nuclei *
there is increases in average number of neutrophil lobes or segments
because of lack of B12 or folic acid
How can you tell there is anaemia from a blood film *
anaemia reduces the viscocity of the blood so cells are more spread out on the film
how can sickle cell lead to Howell-Jolly bodies
polymerisation causes recurrant infarction of spleen = howell-jolly bodies
what does a tetraploid neutrophil look like
–
what is the function of lymphocytes *
humoral and cellular immunity
list the physiological factors that influence the rate of red cell production *
anaemia
hypoxia
increased androgens
what fascilitates oxygen delivery
teh sigmoid oxygen dissociation curve
a lower pH reduces oxygen affinity to Hb = more offloading in met actiuve tissues
