Approximately how many erythrocytes (red blood cells) are present in one drop of whole blood (about 50 microliters) in a healthy adult?

• A. About 250 million erythrocytes
• B. About 25 thousand erythrocytes
• C. About 25 billion erythrocytes
• D. About 2.5 million erythrocytes

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the average concentration of erythrocytes in whole blood. Typically, a healthy adult has about 5 million erythrocytes per microliter of blood.
2. Step 2: Identify the volume of blood in one drop, which is approximately 50 microliters.
3. Step 3: Use the formula to calculate the total number of erythrocytes in one drop: multiply the concentration of erythrocytes per microliter by the volume in microliters. Mathematically, this is expressed as: \(\text{Number of erythrocytes} = 5,000,000 \times 50\).
4. Step 4: Perform the multiplication to find the total erythrocytes in one drop, keeping track of the units to ensure accuracy.
5. Step 5: Interpret the result to match it with the closest option given in the problem, understanding that the number will be in the hundreds of millions range.