2-total Wbc Count

Practical Physiology 2nd Lab.

Total White Blood Cell Count

(Total WBC count) [email protected]

Lab. no. 2: Total WBC Count Follow the same procedure as in case of RBC count, but use the white blood cell pipette of the haemacytometer, which gives a blood dilution of (20) times only. -The white cell pipette has a smaller bulb than the red cell pipette and contains a white bead. The mark above the bulb is designated (11). It requires a larger quantity of blood, so don’t begin to suck until a large drop of blood is available after pricking the thumb. [email protected]

Lab. no. 2: Total WBC Count Fill to the (0.5) mark. The diluting fluid in this case is (1.5%) solution of (acetic acid) in water, tinted with methyl violet (methyl green or gentian violet could be used). The acid destroys the red cell envelopes so that they do not interfere with the count, and the dye colors the nuclei of the white cell making them more prominent. After mixing, the pipette is laid aside for 5 minutes, to ensure complete haemolysis.

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Lab. no. 2: Total WBC Count Then part of the diluting fluid in the capillary tube should be discarded. A drop of diluted blood is then placed on the slide taking the same precautions as in the red cell count. Count the №. of WBC in all the four large corner squares under low power objective(X10). Fine debris of the RBCs should be ignored. Take the mean of the № of WBCs found in these four large corner squares. Say n =

Total №. of WBCs in four large squares 4 [email protected]

Lab. no. 2: Total WBC Count

WBC

WBC

WBC

WBC

Improved Neubauer’s counting chamber

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Enlarged one large corner square depth= 0.1 mm. ;area= 1 mm2. volume= 0.1 mm3.

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● counted ○ not counted

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Lab. no. 2: Total WBC Count Calculation: n is the № of WBCs found in one large square. Since the area of this square is (1mm2) and the depth is (0.1mm); therefore, n represents the № of WBCs in (0.1 mm3) of diluted blood. Therefore, nx10 represents the № of WBCs in 1 mm3 of diluted blood. Since the blood has been diluted 20 times, therefore the № of WBC in 1mm3 of normal blood is: № of WBCs(mm3)=

n x 10 x 20 [email protected]

Lab. no. 2: Total WBC Count Normal values of WBC count: Average adult value is 7000 cell/mm3. Normal range is 4000 - 11000 cell/mm3. At birth is about 20000 cell/mm3. Physiological causes of a rise in WBC count (Leucocytosis) include: 1. Exercise. 2. During infancy.. [email protected]

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