In human blood, which formed element is the most abundant by number in a typical healthy adult?

• A. Erythrocytes (red blood cells)
• B. Platelets (thrombocytes)
• C. Plasma proteins
• D. Leukocytes (white blood cells)

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the types of formed elements in human blood. These include erythrocytes (red blood cells), leukocytes (white blood cells), and platelets (thrombocytes). Plasma proteins are not formed elements but are dissolved in the plasma.
2. Step 2: Recall the primary function and relative abundance of each formed element. Erythrocytes are responsible for oxygen transport, leukocytes for immune defense, and platelets for blood clotting.
3. Step 3: Consider typical counts per microliter of blood: erythrocytes are usually in the millions, platelets in the hundreds of thousands, and leukocytes in the thousands.
4. Step 4: Compare these typical values to determine which formed element is most abundant by number. This involves recognizing that erythrocytes outnumber the others by a significant margin.
5. Step 5: Conclude that erythrocytes (red blood cells) are the most abundant formed element in human blood in a healthy adult.