hematology Flashcards
what is hematology?
it considers the functions of blood that are directly related to its gross cellular composition, cytology, cellular properties and mechanisms such as coagulation
what three measurements give an indication of capability for gas transport or the respiratory function of blood?
erythrocyte numbers, hemoglobin concentration and hematocrit
what does measurement of numbers and proportions of leukocytes used to determine?
the ability to withstand infection and the index of response to infection
what are two methods of blood sampling?
skin puncture and venipuncture
what does EDTA do, what is it used for, what colour is it?
EDTA (disodium/dipotassium ethylene diaminetetracetic acid) chelates calcium; it does not cause platelet clumping, less effect on WBC than oxalates. the preferred anticoagulant for hematology analysis. it is purple top
what does sodium citrate do, what is it used for, what colour is it
binds calcium. used for coagulation studies, erythrocyte sedimentation rate and transfusion purposes. non-toxic, metabolized readily, and preserves coagulation factors. blue
what does heparin do, what is it used for, what colour is it?
heparin inhibits thrombin and other activated clotting factors through activation of antithrobin III. (don’t use for coagulation studies!)
preferred for osmotic fragility tests. not good for blood morphology staining. green
what do oxalates do and what colour is it?
precipitates calcium as calcium oxalate. not used much any more. can be used for some coagulation studies and osmotic fragility measurements. grey
what does sodium fluoride do?
not used for hematological work; stopes RBC glycolysis so frequently used with blood samples for metabolite assay
what is rouleaux formation?
stacks of RBCs that form because of the discoid cell shape in vertebrates. more common in horses (and cats?)
what is hemolysis?
lysis of red blood cells
what is an erythrocyte ghost?
the membrane and cytoskeletal elements of the erythrocyte devoid of cytoplasmic contents but preserving the original morphology
what does a hemocytometer allow you to measure?
the number of cells per unit of volume
how would you use a hemocytometer to measure leukocytes in a blood sample?
use a diluting fluid that lyses the red blood cells
how is a reticulocyte count performed?
count 1000 cells and identify as a reticulocyte or mature erythrocyte and then express as % of the total number of erythrocytes (usually more meaningful if expressed per litre)
what is a stain that can allow easy visualization of reticulocytes?
new methylene blue stain. it causes ribosomes and polyribosomes containing RNA to clump into granules (it is as a supravital stain)
how is a WBC count made?
with a hemocytometer
what is a leukopenia?
a decrease in total WBC count and may arise from viral infections