Kaplan Nursing Entrance Practice Exam

What is the most abundant type of cell in the blood?

1. White blood cells

2. Platelets

3. Red blood cells

4. Lymphocytes

The correct answer is: Red blood cells

Red blood cells are the most abundant type of cell in the blood, making up about 40-45% of blood volume in a healthy individual. Their primary function is to transport oxygen from the lungs to the rest of the body and carry carbon dioxide back to the lungs for exhalation. The high number of red blood cells is critical for meeting the oxygen demands of the body's tissues and organs. While white blood cells, platelets, and lymphocytes play important roles in the immune response and clotting processes, they are present in much smaller quantities compared to red blood cells. White blood cells represent a small fraction of blood cells, primarily tasked with defending against infections and foreign invaders. Platelets, though essential for blood clotting and wound healing, are even less numerous. Lymphocytes, a subtype of white blood cells, contribute to specific immunity, but also exist in lower counts than red blood cells. Understanding the primary functions and distribution of these cells highlights the essential role of red blood cells in the circulatory system and overall human health.