Total RBC Count and Normal Values

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Questions and Answers

What is the primary function of red blood cells?

To assist in clotting

To fight infections

To carry oxygen (correct)

To regulate body temperature

What percentage of blood volume do red blood cells constitute?

40%

45% (correct)

25%

50%

What is a common characteristic of red blood cells that distinguishes them from other cells?

Packed with hemoglobin (correct)

Presence of a nucleus

Ability to replicate

High metabolism rate

Which factor can lead to a low red blood cell count?

Iron deficiency Signup and view all the answers

How does the RBC count vary between genders?

Women usually have a lower RBC count than men Signup and view all the answers

What could a decreased RBC count during pregnancy indicate?

Normal physiological change Signup and view all the answers

At what age range do children show normal RBC count values?

3.8 - 5.5 million Signup and view all the answers

What can a complete blood count (CBC) help diagnose?

Blood-related conditions Signup and view all the answers

Which of the following health conditions can lead to a high RBC count?

Hypoxia Signup and view all the answers

What is the primary function of a haemocytometer?

To count cells in a fluid Signup and view all the answers

Which part of the haemocytometer grid allows for accurate volume measurements?

Raised edges holding the coverslip Signup and view all the answers

What is the appropriate volume of an RBC diluting fluid required for a hemocytometer analysis?

1 ml Signup and view all the answers

Which component in Haeyem’s solution acts as an antiseptic?

Mercuric Chloride Signup and view all the answers

Which specific structure can lead to a high RBC count due to a health condition present at birth?

Congenital heart disease Signup and view all the answers

What is one reason a high RBC count could be observed over several weeks?

Living at a higher altitude Signup and view all the answers

Which of the following is NOT a characteristic of the Improved Neubauer ruled Haemocytometer?

Engraved with random lines Signup and view all the answers

What is the primary purpose of using the RBC diluting fluid with the blood sample?

To achieve a specific dilution ratio for counting Signup and view all the answers

Which of the following steps is NOT part of preparing the blood sample for counting?

Heating the blood sample to increase fluidity Signup and view all the answers

What is the correct angle at which the RBC pipette should be held when loading the sample into the Haemocytometer?

45 degrees Signup and view all the answers

How long should the prepared RBC slide be allowed to settle before observation under the microscope?

3-5 minutes Signup and view all the answers

When focusing on the Haemocytometer slide, which objective lens should initially be used?

10X objective lens Signup and view all the answers

Which of the following areas on the Haemocytometer slide should NOT have RBCs counted?

Upper right corner Signup and view all the answers

What is the significance of using a sterile disposable lancet during blood sampling?

To prevent contamination and infection Signup and view all the answers

What indicates the areas to count red blood cells in the Haemocytometer?

Green lines Signup and view all the answers

Signup and view all the answers

Study Notes

Total RBC Count

A red blood cell (RBC) count is a blood test measuring the number of red blood cells (erythrocytes) in the body.
RBCs make up approximately 45% of blood volume.
RBCs transport oxygen from the lungs to body cells.
RBCs contain hemoglobin, a protein-iron compound that captures oxygen in the lungs, giving blood its red color.
RBCs lack a nucleus, unlike other cells.
The amount of oxygen delivered to tissues depends on the number of RBCs and their function.
RBC counts are part of full blood cell counts (FBC) or complete blood counts (CBC).
Women typically have lower RBC counts than men; counts decrease with age.

Normal RBC Values

Normal RBC values vary by age:
- Newborn: 4.8-7.2 million/µL
- Adult males: 4.9-5.5 million/µL
- Adult females: 4.4-5.0 million/µL
- Pregnancy: slightly lower than normal adult values
- Children: 3.8-5.5 million/µL

Low RBC Count Causes

Iron deficiency anemia (low RBC count)
Vitamin B6, B12, or folate deficiency
Internal bleeding
Kidney disease
Malnutrition

High RBC Count Causes

Smoking
Congenital heart disease
Dehydration (severe diarrhea)
Low blood oxygen levels (hypoxia)
Pulmonary fibrosis
Congenital heart defects
High altitude

Hemocytometer

A hemocytometer (or improved Neubauer) is a microscope slide with a grid for counting cells.
The grid has precisely defined dimensions for accurate cell counts in a specific volume.
Invented by Louis-Charles Malassez.
The grid's area and depth are precisely known.
This allows counting cells in a specific volume of fluid, and thus determining cell concentration.
A common type is the Neubauer counting chamber.
The grid is divided into smaller squares.

Hemocytometer Grid Specifications

The grid area of the Improved Neubauer is 9 squares (1 mm x 1 mm).
Each square is subdivided into smaller squares of different sizes, including - 0.25 x 0.25 mm (0.0625mm2) - 0.25 x 0.20 mm (0.05mm2) - 0.20 x 0.20 mm (0.04mm2) - 0.05 x 0.05 mm (0.0025mm2)
Each square has a set volume at a specific depth (e.g., 0.1 mm)

RBC Enumeration Materials

Hemocytometer chamber
Cover slip
Light microscope
Pipette for RBCs
RBC diluting fluid (e.g., Hayem's solution or 0.85% saline)

Hayem's Solution Details

Composition: Sodium chloride, sodium sulfate, and mercuric chloride
Sodium chloride (NaCl): 1 gram
Sodium sulfate (Na2SO4): 5 grams
Mercuric chloride (HgCl2): 0.5 gram
Distilled water (dH20): 200 mL
Used to dilute blood prior to counting.

Taking Blood Sample

Wipe the ring finger with 70% alcohol and allow to dry.
Sterile disposable lancet creates a small prick.
Collect a reasonable-sized blood drop.
Apply the red blood cell pipette's tip to the drop.
Aspirate blood to the 0.5 mark.

Sample Preparation using RBC Pipette

Wipe RBC pipette tip with blotting paper to remove blood.
Draw up RBC diluent to the 101 mark.
Mix blood and diluent in the pipette by rotating it.
Rotate for 2-3 minutes to ensure complete hemolysis of white blood cells.

Loading Sample onto Hemocytometer

A clean, grease-free hemocytometer and cover glass are used.
The cover glass is placed on top of the hemocytometer's grid.
Discard one or two drops of the blood/diluent mixture.
Load a small drop of mixed blood and diluent onto the edge of the cover glass.
Let the sample settle for 3–5 minutes.
Examine the slide under the microscope.

Counting RBCs Under Microscope

Focus on hemocytometer rulings using 10x objective.
Use coarse and fine adjustments to focus 5 squares on the large central square at 40x objective magnification.
Each large square contains 16 smaller squares.
Manually count RBCs in 5 medium squares (80 squares total)
The diagram shows red lines not to count and green lines specifying the areas to count.

Calculating Total RBC Count

Formula for total RBC count per microliter (µL): Number of RBCs counted x Dilution factor / Area x Depth
Using example,
- The dilution factor is 1:200 or 200
- The area of 5 squares out of 25 squares in a large square is 1/5 mm2 or 0.2 mm
- Depth of sample = 0.1 mm
Total RBCs/µL = Number of RBCs x 200 / 1/5 x 0.1 mm = N x 10,000 cells/µL
An example calculation assuming 486 RBCs are counted in 5 squares:
486 x 10,000 = 48,60,000 cells/µL

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Description

This quiz covers the essential aspects of red blood cell (RBC) counts, including their function, normal values by age, and causes of low RBC counts. Gain an understanding of how RBCs transport oxygen and the variations in counts among different populations. Test your knowledge on the significance of RBCs in blood health.