Patient Care Technician (PCT) AAH Practice Exam

Which of the following blood components is primarily responsible for gas exchange?

1. Plasma

2. Red blood cells

3. Platelets

4. White blood cells

The correct answer is: Red blood cells

Red blood cells are primarily responsible for gas exchange in the body. Their main function is to transport oxygen from the lungs to tissues throughout the body, and to carry carbon dioxide back from the tissues to the lungs for exhalation. Each red blood cell contains hemoglobin, a protein that binds to oxygen molecules, which allows for efficient oxygen transport. In contrast, the other blood components serve different roles. Plasma is the liquid portion of blood that carries nutrients, hormones, and waste products, but it does not play a direct role in gas exchange. Platelets are involved in blood clotting and tissue repair, essential for wound healing and preventing excessive bleeding. White blood cells function primarily in the immune response, helping to fight infections and foreign substances, rather than being involved in gas transport or exchange. This distinction clarifies why red blood cells are essential for respiratory functions, as they enable the effective delivery of oxygen necessary for cellular metabolism.