Flashcards for Lab Prep

Question 1

For a blood smear, how much blood should be added to the slide?

Answer 1

6 μl

Question 2

What end should the frosting be at?

Answer 2

Right

Question 3

In a good blood smear, what are you looking for?

Answer 3

Nice smooth spreading on the slide, margin of white blood cells around the periphery

Question 4

What angle should the blood be spread at?

Answer 4

30°

Question 5

How full should the microhaematocrit tube be to calculate PCV?

Answer 5

3/4 full

Question 6

How many times should the microhaematocrit tube be inserted into the wax and why?

Answer 6

Twice to ensure a good seal

Question 7

Why should the finger always be on the top of the microhaematocrit tube?

Answer 7

To prevent blood from leaking

Question 8

How is the packed cell volume (PCV) calculated?

Answer 8

(Distance red blood cells travelled / distance blood sample travelled) x 100

Question 9

What dilution of blood is used for the absolute white blood cell count?

Answer 9

1:20 (50 μl:950 μl)

Question 10

What solution is used to dilute the blood for the absolute white blood cell count?

Answer 10

Erythrocyte lysis buffer A

Question 11

After mixing, how long should the white blood cell count solution have to stand?

Answer 11

2 minutes

Question 12

What dilution of blood is used for the absolute red blood cell count?

Answer 12

1:200 (5 μl:995 μl)

Question 13

What solution is used to dilute the blood for the absolute red blood cell count?

Answer 13

PBS

Question 14

After mixing, how long should the red blood cell count solution have to stand?

Answer 14

None (instantly)

Question 15

What dilution of blood is used for the absolute platelet count?

Answer 15

1:20 (50 μl:950 μl)

Question 16

What solution is used to dilute the blood for the platelet cell count?

Answer 16

Erythrocyte lysis buffer B

Question 17

After mixing, how long should the platelet count solution have to stand?

Answer 17

At least 10 minutes

Question 18

How should the samples be loaded into the haemocytometer?

Answer 18

Top down, in the gap between the coverslip and the grid

Question 19

How much of the sample should be loaded into each chamber of the haemocytometer?

Answer 19

10 μl

Question 20

What setting on the microscope makes it the easiest to count cells?

Answer 20

Phase contrast

Question 21

How can red blood cells and platelets be visualised on the haemocytometer?

Answer 21

Using the small central grid

Question 22

How can white blood cells be visualised on the haemocytometer?

Answer 22

One of the four large corner grids

Question 23

What cells should be counted?

Answer 23

To save counting some twice, only those cells that fall within each square or lie on two of the four border lines of each should be counted

Question 24

What is the formula to calculate the viable cell density?

Answer 24

Average corner count x 10⁴ x Dilution factor

Question 25

What is the formula to calculate the percentage viability?

Answer 25

Total viable cell count / Total cell count x 100

Question 26

How to recognise a neutrophil

Answer 26

~62-70% of total WBC count, 10-12 μm in diameter, mulitlobed nucleus with fine/faintstained cytoplasmic granules

Question 27

How to recognise an eosinophil

Answer 27

~2.3% of total WBC count, 10-12 μm in diameter with a bi-lobed nucleus, cytoplasmic granules are heavily stained with eosin

Question 28

How to recognise a basophil

Answer 28

~0.4% of total WBC count, 12-15 μm in diameter with bi/tri-lobed nucleus, cytoplasmic granules are large heavy blue stained

Question 29

How to recognise a lymphocyte

Answer 29

30% of total WBC count, small = 7-8 μm and large + 12-15 μm in diameter with darkly stained eccentric nucleus with small amount of cytoplasm

Question 30

How to recognise a monocyte

Answer 30

~5.3% of total WBC count, 8-10 μm in diameter with a kidney shaped nucleus, granular with abundant cytoplasm

Question 31

What is the average number of red blood cells per μl?

Answer 31

4-6 x10⁶

Question 32

What is the average number of white blood cells per μl?

Answer 32

4-11 x 10³

Question 33

What is the average number of lymphocytes per μl?

Answer 33

1.3-4.0 x 10³

Question 34

What is the average number of neutrophils per μl?

Answer 34

2-8 x 10³

Question 35

What is the average number of monocytes per μl?

Answer 35

0.2-0.8 x 10³

Question 36

What is the average number of platelets per μl?

Answer 36

1-4 x 10⁵

Question 37

What is a normal person's international normalised ratio (INR) range?

Answer 37

0.9-1.3

Question 38

What is a warfarin patient's international normalised ratio (INR) range?

Answer 38

2-3

Question 39

What is the reference range for PT of normal plasma?

Answer 39

12-15 seconds

Question 40

Method for prothrombin (PT) test

Answer 40

1. Add to 100 μl plasma to 200 μl of PT reagent. Start the stopwatch 2. Incubate with gentle agitation 3. The endpoint (given in seconds) is where the clot forms 4. Repeat the assay and calculate the mean

Question 41

What is the reference range for APTT of normal plasma?

Answer 41

25-45 seconds

Question 42

Method for activated partial thromboplastin time (APTT) test

Answer 42

1. Mix 100 μl plasma sample with 100 μl APTT reagent in a 12x77 mm borosilicate glass tube & incubate for 3 minutes 2. Add 100 μl CaCl₂ solution & simultaneously start stopwatch 3. Leave tube for about 20 seconds then gently tilt the tube to observe clotting 4. The endpoint (given in seconds) is when the clot forms 5. Repeat the assay and calculate the mean