Help with microscope (1 Viewer)

[louweesel]

I was wondering if someone could explain to me the process of estimating size for white and red blood cells. I know it vaguely but I am not completely sure of the process. MAJOR BRAIN SCRAMBLE!!!

 

[Lori.]

This is copied directly out of Heinemann Activity Manual (prac 5.5)

1. Focus a ruler or graph paper under low power and observe the millimetre markings.
2. Record the diameter of the LP field in millimetres to one decimal place. Convert this to micrometres (multiply by 1000).
3. Calculate the diameter of your HP field and record this in micrometres.
4. focus the prepared slide under LP and distinguish the numerous tiny red cells and the occassional, larger white cells.
5. Focus on HP and observe the cells more closely.
... [unrelated instructions...]
8. Recall the diameter of the field of view and estimate the size of each type of cell.

I wasnt actually in class when we did this prac, which has cost me so many marks in the half yearly and trial

The results of the prac would have been something like;
'the diameter of a HP view is x, and y amount of red blood cells fit across the diameter, so x/y is the size of a red blood cell...'

The size of a red blood cell is around 7 micrometers, and white blood cells can be between 10 and 26 micrometers (my teacher told us that the markers should accept anything between 10 and 26 micrometers)

 

[ali777]

here's my class notes on the experiment:



AIM To estimate the size of RBCs and WBCs

RISK ANALYSIS / SAFETY PRECAUTIONS
Broken slides may cause cuts - put in bin with dustpan & brush, avoid touching broken glass. Using a fresh blood sample poses a risk of contracting any blood borne diseases eg HIV, hepatitis. Use a commercial blood slide / prepared blood slide.

EQUIPMENT
Commercial blood slide, light microscope, minigrid, pencil, ruler, calculator.

METHOD
• Set up microscope
• Focus on 0.1mm² minigrid at 400x magnification. Count number of squares across diameter, thus estimating field of view. eg if 4 squares can fit across, then field of view is approximately 0.4mm or 400µm wide (1000µm = 1mm)
• Remove minigrid & replace with commercial blood slide. Using 400x magnification, count/estimate the number of RBCs across field of view. Eg 50 RBCs fit across field of view
• Divide field of view by number of RBCs (400µm / 50) therefore each blood cell is approximately 8µm in diameter.
• WBCs are roughly 1.5x larger than RBCs. Therefore WBCs are approximately 12µm in diameter.



good luck!
Ali