Which formed element of the blood is responsible for transporting oxygen?

The formed element of the blood responsible for transporting oxygen is the erythrocyte, also known as a red blood cell. Erythrocytes contain hemoglobin, a specialized protein that binds to oxygen molecules in the lungs and releases them in tissues throughout the body. This oxygen transport function is critical for cellular respiration, where cells utilize oxygen to produce energy.

Leukocytes, or white blood cells, primarily play a role in the immune response and help defend the body against infections. They do not have a significant function in oxygen transport. Platelets are not involved in oxygen transport either; their main role is in blood clotting and preventing bleeding. Plasma, the liquid component of blood, serves as a medium for transporting nutrients, hormones, and waste products, but it does not directly transport oxygen in the way that erythrocytes do.