What is the primary function of erythrocytes?

Erythrocytes, also known as red blood cells, have a primary function centered around the transportation of oxygen from the lungs to the tissues throughout the body. This critical role is facilitated by hemoglobin, a protein within erythrocytes that binds to oxygen molecules. When blood circulates through the lungs, erythrocytes pick up oxygen, which is then delivered to various tissues where it is used in cellular respiration to produce energy.

In addition to oxygen transport, erythrocytes also aid in transporting a small amount of carbon dioxide—a waste product of cellular metabolism—back to the lungs for exhalation. This dual function is vital for maintaining the body’s metabolic processes and overall homeostasis.

While some of the other choices pertain to functions in the circulatory system, such as forming blood clots (which is primarily the role of platelets) or transporting hormones (which is generally the role of plasma or specific carrier proteins), these are not the primary functions of erythrocytes. Their unique structure, which is adapted for flexibility and increased surface area, enables efficient gas exchange, underscoring the specificity of their role in oxygen transport.