Manual RBC Count Techniques

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Questions and Answers

What is the primary function of erythrocytes in the blood?

Transport nutrients

Combine with O2 and CO2 (correct)

Produce antibodies

Regulate body temperature

What is the normal range of RBC count for a healthy adult male?

4 - 5 million cells/mm³

4.5 - 6 million cells/mm³ (correct)

5 - 7 million cells/mm³

3 - 4 million cells/mm³

What is used as a diluting solution when counting RBCs?

Ethanol

Distilled water

Saline solution

Hayem's solution (correct)

Which of the following materials is NOT required for a manual RBC count?

Spectrophotometer (C) Signup and view all the answers

What is the appearance of erythrocytes?

Biconcave (A) Signup and view all the answers

What is a common lifespan of erythrocytes in circulation?

120 days (A) Signup and view all the answers

What is the main purpose of a RBC count?

To determine the number of circulating RBCs per mm³ of blood (B) Signup and view all the answers

What is the depth of the hemocytometer used for RBC counting?

0.1 mm (C) Signup and view all the answers

Which factor might cause errors in RBC counting?

Sample dilution time (C) Signup and view all the answers

Which condition is characterized by a decrease in the number of RBCs below the normal range?

Anemia (A) Signup and view all the answers

What can cause physiological polycythemia?

High altitude (A) Signup and view all the answers

What is the total area of each primary square in the counting chamber?

9 mm² (D) Signup and view all the answers

What is the significance of primary polycythemia?

It occurs in individuals with bone marrow malignancy. (A) Signup and view all the answers

Which of the following is NOT a source of error in a manual RBC count?

Using a calibrated counting chamber (B) Signup and view all the answers

How many smaller secondary squares are present in the central primary square?

25 (B) Signup and view all the answers

Which primary squares are used for counting white blood cells (WBCs)?

Four corner primary squares (C) Signup and view all the answers

What should you do after drawing blood into the RBC’s pipette?

Complete to 101 with RBC’s diluting solution (B) Signup and view all the answers

For how long should the hemocytometer stand on the bench after loading it with diluted blood?

3-5 minutes (A) Signup and view all the answers

Which magnification lens is used to count RBCs in the hemocytometer?

40X (C) Signup and view all the answers

How should a drop of diluted blood be introduced into the hemocytometer?

Let it run between the slide and cover slip by capillary action (D) Signup and view all the answers

How many corner squares should be counted for RBCs?

Four corner squares (A) Signup and view all the answers

What should be included in the count of cells touching the upper and left lines?

Cells touching any of the upper and left lines (A) Signup and view all the answers

What is the dilution factor used in the RBC’s count calculation?

200 (D) Signup and view all the answers

What is the volume correction factor when the counted volume is 0.02 mm³?

50 (D) Signup and view all the answers

How many small squares are counted in the RBC’s count method described?

80 (B) Signup and view all the answers

What should the variation between two R squares not exceed?

20 cells (D) Signup and view all the answers

How is the counted volume for 5 medium squares calculated?

(width x length x depth) x 5 (B) Signup and view all the answers

What is the volume of each medium square if using 1/5 mm dimensions?

0.02 mm³ (A) Signup and view all the answers

Study Notes

Manual RBC Count Objectives

Utilize a hematocytometer to count red blood cells (RBCs).
Estimate circulating RBCs per mm³ of blood.
Understand physiological and pathological variations in RBC counts.
Identify factors causing errors in RBC count.

RBC Characteristics

Total erythrocyte count is expressed as RBCs/mm³ blood.
Erythrocytes are biconcave, nucleated cells containing hemoglobin, crucial for oxygen transport.
Average lifespan of RBCs is approximately 120 days.

Normal Range of RBCs

Healthy adult male: 4.5 - 6 million cells/mm³.
Healthy adult female: 4 - 5.5 million cells/mm³.

Procedure Overview

Dilute blood sample with isotonic solution (Hayem's solution) for counting.
Use a RBC diluting pipette, hemocytometer, and microscope.

Hemocytometer Details

Consists of two square ruled areas with a depth of 0.1mm.
Each primary square is divided into 9 secondary squares.
Central primary square (25 secondary squares) is used for RBC counting.

RBC Counting Procedure

Draw blood to the 0.5 mark on pipette; complete up to 101 with Hayem's solution.
Mix and then load diluted blood onto the hemocytometer, allowing it to settle for 3-5 minutes.
Count RBCs in the central medium square and four corner medium squares using a microscope at 40X magnification.

Calculation of RBC Count

Total counted cells in the five squares are noted, ensuring variation doesn't exceed 20 cells.
Correct count formula: Number of RBCs/mm³ = (counted cells in 5 squares) x (diluting factor) x (volume correction factor).
Example dilution factor: DF = (101 – 1) / 0.5 = 200.

Volume Correction

For volume correction: Counted volume = (width x length x depth) x number of squares.
Volume correction factor: VCF = 1 mm³ / counted volume.

Example Calculation

If 423 RBCs counted in 5 squares:
- RBC count in 1 mm³ = 423 x 200 x 50 = 4,230,000.

Clinical Significance

RBC count helps assess oxygen delivery to tissues; low counts can reduce oxygen availability.
Anemia indicates decreased RBC count; polycythemia indicates increased RBC count.

Types of Polycythemia

Physiological (up to 8 million cells/mm³) can occur due to age or high altitude.
Pathological:
- Primary: Over 14 million cells/mm³ due to bone marrow malignancies.
- Secondary: Over 8 million cells/mm³ due to respiratory or heart diseases.

Sources of Error in RBC Counting

Excessive sample flooding in the chamber.
Missing cells in the count or including artifacts.

Videos for Reference

Relevant instructional videos can provide additional visual aid to the counting process.

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Description

This quiz covers the manual counting techniques for red blood cells (RBCs) using a hematocytometer. You will explore the physiological and pathological implications of RBC count variations, along with common sources of error in counting. Test your knowledge on estimating the number of circulating RBCs per mm³ of blood.