Kaplan Nursing Entrance Practice Exam

What is the primary function of red blood cells?

1. Fight infections

2. Transport oxygen

3. Clot blood

4. Regulate body temperature

The correct answer is: Transport oxygen

The primary function of red blood cells, also known as erythrocytes, is to transport oxygen from the lungs to the tissues throughout the body. This process is essential for cellular respiration, as oxygen is needed by cells to produce energy. In addition to oxygen transport, red blood cells also play a role in carrying carbon dioxide back to the lungs for exhalation. They achieve this through the hemoglobin, a protein within the cells that binds to oxygen and allows for efficient transport. In contrast, other functions mentioned in the options are associated with different types of blood cells or bodily systems. Fighting infections is primarily the role of white blood cells, which are part of the immune system. Clotting blood is the main function of platelets, which help prevent excessive bleeding when injuries occur. Regulating body temperature is managed through a combination of mechanisms, including blood flow and sweat production, rather than directly through the function of red blood cells. Therefore, the clear and established role of red blood cells in oxygen transport makes this the correct answer.