Oregon Certified Nursing Assistant State Practice Exam

What is the function of red blood cells?

1. To fight infection

2. To carry oxygen to the body’s tissues

3. To help in blood clotting

4. To produce hormones

The correct answer is: To carry oxygen to the body’s tissues

Red blood cells, also known as erythrocytes, primarily have the essential function of carrying oxygen from the lungs to the body's tissues and returning carbon dioxide from the tissues back to the lungs. The hemoglobin contained within red blood cells binds oxygen in the lungs, where oxygen concentration is high, and releases it in the tissues, where the concentration is low. This crucial role is vital for cellular respiration, as oxygen is necessary for cells to produce energy. The other functions mentioned, such as fighting infection, helping in blood clotting, and producing hormones, are primarily carried out by other types of blood cells or components. White blood cells are responsible for fighting infection, platelets play a key role in blood clotting, and various cells within the body are responsible for hormone production. Therefore, the core function of red blood cells is distinct and fundamental to maintaining oxygen supply throughout the body.