HEMA LEC MIDTERM: CELL COUNT

What is a CBC?

A CBC is a panel of tests that evaluates the three types of cells that circulate in the blood

What is one use of CBC?

Screen for a wide range of conditions and diseases

What is another use of CBC?

Help diagnose various conditions, such as anemia, infection, inflammation, bleeding disorder or leukemia

What is another use of CBC?

Monitor the condition and/or effectiveness of treatment after a diagnosis is established

What is another use of CBC?

Monitor treatment that is known to affect blood cells, such as chemotherapy or radiation therapy

What is qualitative counting?

Based on the structure or morphology of the cells

What is quantitative counting?

Based on the actual count of cells made in Hemacytometer Counting Chamber or using an Automated cell counter.

What are the units used for relative count?

%

What are the units used for absolute count?

cells X 10^12/L

What is the first step in the Cell Counting Method?

Dilution of Blood

What is the second step in the Cell Counting Method?

Sampling the diluted blood into a measured volume

What is the third step in the Cell Counting Method?

Counting the cells in that volume

What are the characteristics of the cover glass?

made with precision; free from visible defects; free from scratches; optically plane on both sides

What is the error of the cover glass?

+ - 0.002 mm

What dilutions does the WBC pipette produce?

1:10 and 1:20 dilution

What dilutions does the RBC pipette produce?

1:100 and 1:200

For standardizing, what system must be used for pipetting and dilution?

The unopette System

What are the advantages of the unopette System?

Safe; Precise; Accurate

What is the reservoir of the unopette System?

contains the premeasured volume of diluting fluid and is sealed by a thin covering of plastic (diaphragm)

What is the pipette of the unopette System?

color coded

What is located at the end opposite the pipet tip of the unopette?

the overflow chamber

What are the requirements of diluting solutions?

must be isotonic(RBC) hypotonic for WBC; must have a buffer action; must contain a fixative; must not contain yeasts or molds; must have a high specific gravity; must be cheap or economical

What must the diluting solution be for RBC?

isotonic

What must the diluting solution be for WBC?

hypotonic

What is noted about Normal Saline Solution?

Specific gravity is low but it could disperse rouleaux formation of cells

What are the advantages/properties of Dacie’s Diluent?

Easy to prepare; Cheap; Keeps well (more stable); does not cause red cell shape alteration; sample may stand for hours

What counting chamber area is used for eosinophil count?

FUCHS ROSENTHAL CHAMBER

What variation in technique is used for Polycythemia?

The dilution is increased(0.3mark)

What variation in technique is used for Anemia?

The dilution is decreased.

What are the sampling errors for capillary blood?

Failure to obtain free flowing blood w/o local pressure; Excessive massage or pressure at the area

What are the sampling errors for venous blood?

Partial Coagulation; Prolonged stasis due to equipment

What are other cell-counting errors?

Clumping or aggregation of cells; Inadequate mixing of the blood sample; Hemolysis due to dirty or wet equipment or excessive trauma

What are the “Others” sources of error?

time relationship to exercise; meals

What are the technical errors?

Unclean or wet pipet or counting chamber

What happens to blood volume during an aerobic exercise program?

In aerobic exercise program, blood volume increases rapidly during the first few weeks, then eventually levels off.

What causes the initial expansion in blood volume during exercise?

This initial expansion is due mostly to an increase in blood plasma, resulting in a decline in hematocrit.

What is the exercise-related decline in hematocrit called?

sports anemia

Is sports anemia true anemia according to the source?

This is called sports anemia, but it is a normal response to exercise, rather than true anemia.

When is erythropoietin secreted according to the source?

Erythropoietin is secreted when low oxygen levels are low.

How long do erythrocytes live in endurance athletes according to the source?

about 70 days

How long do erythrocytes live according to the comparison in the source?

about 120 days

What factors are associated with destruction of red blood cells during exercise?

Increases in body temperature during exercise and oxidative stress.

What appears to be the main cause of red blood cell destruction during exercise?

trauma to the blood cells, most often due to the pounding of the feet in running.

What is the counting error for skilled medical technologists?

The error is expressed as +- 2 CV which is approximately 4.2%.