hem lab 2-4 5 6
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what is the name of special slide used to perform manual cell count?
what are the 3 functions pf coverglass when it is in place on hemacytometer
- creates chamber
- confines fluid when chamber is loaded
- regulates the depth of the fluid
why is it important to ensure that fluid does not overflow into the moats ?
if it will overflow into the moats it will alter cell distribution.
what process should be used to clean the hemacytometer and coverglass after use?
- soaked in 10% chlorine bleach
- washed in solution of laboratory detergent
- thoroughly rinsed
what is the general formula for cell count calculation ?
- celles/μL = Cells/mm3 =
- ave x DF/ A(mm2) x D(0.1mm)
final cell count
sum of cells counted on both sides of hemacytometer divided by 2
- depth of chamber
- always = 0.1 mm
if 1:200 dilution is made, how maby parts of blood to diluting fluid would you use?
1 part of blood + 199 parts of diluting fluid
Explain boundary rule?
- Count should start in the upper left corner and continue in a serpentine manner.
- Cells that are w/in the square, that touch left boundary, and/or touch top boundary are COUNTED.
- Cells that touch the right boundary, and/or lower boundary are NOT COUNTED
what are the reference WBC values for newborn, children and adults?
- Newborn: 18,000 ( 1.8x1010)
- 1 y.o: 11,000
- 6 y.o: 8,000
- Adult: 7,400
name 3 causes of leukocytosis
name 3 factors that can cause Leukopenia?
- viral infection
- exposure to ionizing radiation
- certain chemicals
- chemotherapy drugs.
where do platelets originate?
from megakaryocytes that are in the bone marrow
what is the function of platelets?
help to initiate blood clotting when injury to blood vessel occurs.
Name a condition in which thrombocytosis can occur?
- strenuous exercise
- living at high altitudes
- hemolytic anemia
- surgical removal of spleen
name a cause of thrombocytopenia
- any condition that is toxic to the bone marrow
- chemotherapy, radiation therapy
- some anemias and leukemia
- Immune thrombocytopenic purpura (ITP)
why is it important to thoroughly clean the coverglass and hemacytometer before performing the platelet count ?
to avoid mistaking dirt particles for platelets
what is the purpose of placing the loaded hemacytometer in the moist chamber?
- prevent evaporation
- allow platelets to settle so they can be more accurately counted
what area of hemacytometer is used to count platelets?
what is the formula for platelet count?
- platelets/μL =
- average # of platelets x 100 / 1 x 0.1
basically: ave # of platelets x 1000/μL
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