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21 Cards in this Set

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  • Back
Define Hematocrit.
The volume of erythrocytes packed by centrifugation in a given volume of blood and expressed as a percentage; abbreviate 'crit' or 'Hct'.
What are the two methods for determinig hematocrits?
1. The manual method [microhematocrit] in which small volume of blood is used. Whole blood is centrifuged in narrow capillary microhematocrit tubes.

2. Analyzer method that electronically calculated by hematology analyzers. It measures percentage of red cells to plasma.
What is the hematocrit range for Adult males and females; Children?
Males 42-52%
Females 36-38%
Children 32-42%
The following has what effect on Hct values?
Severe dehydration
High altitudes
Dehydration: Increase
Anemias: Decrease
Polycythemia: Increase
Leukemias: Decrease
High altitudes: Increase
Specimens for the hematocrit testing can be collected by?
Capillary puncture
Intravenous blood in EDTA.
What is the procedure for Hematocrit testing?
1. Fill two capillary tube from puncture or tube of blood.

2. Seal ends

3. Place sealed tubes in microhematocrit centrifuge with sealed ends against the rubber gasket and open end toward center (tubes must be on oposites to be even) Run for 2-5 minutes.

4. Place tubes on a hematocrit reader. The two values of both tubes should not vary more than 1%.
Define Hemacytometer.
A heavy glass slide made to precise specifications and used to count cells microscopically: a counting chamber.
Define hemacytometer coverglass.
Coverglass of uniform thickness used with hemacytometer.
Describe the features of a Hemacytometer.
A. Must be used with a hemacytometer cover glass of uniform thickness.

B. 2 polished platforms surrounded by 3 depressions

C. Each platform has a ruled counting area that is etched, marked off by precise lines.

D. The cover slip will cover both sides (or platforms) evenly of the counting area and will create an area called a chamber.

E. The chamber is what regulates the depth of fluid.

F. 0.1 mm in depth
What is the WBC counting area on the hemacytometer?
The WBC counting area using the unopette method consists of all nine large squares.
What is the RBC counting area?
The large center square is used for RBC counts. The center square is subdivided into 25 smaller squares which in turn are each divided into 16 squares.
What is charging the hemacytometer?
When a coverglass is positioned so it covers both ruled areas, then the hemacytometer is filled or charged. Filling is done by by tuching the tip of a micropipet to the point on one side where the coverglass and raised platform meet. The fluid is allowed to flow by capillary action into one side, using one drop of fluid. The opposite side is filled int he same manner. Fluid should not overflow and should settle 2 or 3 minutes. Waiting too long dries the blood and counts will be inaccurate.
Explain Viewing under the microscope:
1. Place hemacytometer on microscope stage with lower power of 10x and locate ruled areas.

2. Use course adjuster to move hemacytometer and objective close toegether unil the objective is almost touching coverglass. Continue until etched lines come into view.

3. The high power 40x is rotated into place. Oil immersion objective is never used with a hemacytometer.
What is a counting pattern?
Lef to right, right to left to ensure cells are counte only once.
Unopette - used for making dilutions to perform cell counts
A. Sealed reservoir containing diluted fluid.

B. For the white blood cells and platelets there will be 1.98 ml of dilatants. Add .02 or twenty ml of whole blood. This will give you a 1:100

C. Red blood cells will have 1.99 of diluents and will add .01ml of blood which will give a 1:200 dilution.

Always remember that white blood cells are a 1:100
What are the ranges for the following?
Adult male
Adult female
Adult Male: 4.5-6.0 x10-
Adult Female: 4.0-5.5 x 10-
Newborn: 5.0-6.3 x 10-
Conditons affecting RBC counts. What are the effects?
Anemias (iron, sickle cell, b12 deficiency, folic acid deficiency)

Polycythemia vera
Anemias: decreased

Erythocrytosis: Increased

Polycythemia vera: Increase
In adults is the WBC higher or lower compared to children?
What are some pathological causes of Leukocytosis (too many WBC)
Infection, Leukemias, Polycythemia
What are some pysiological causes of leukocytosis?
Exposure to sunlight
Obstetric labor
Stress Anethesia
What are some pathological causes of Leukocytopenia (too few WBC)
Viral infections including HIV, ionizing radiation, certain chemicals, chemotherapy drugs.