Which cell type is primarily involved in oxygen transport in the bloodstream?

Which cell type is primarily involved in oxygen transport in the bloodstream?

• A. Erythrocyte
• B. Leukocyte
• C. Platelet
• D. Plasma

Answer: (A)

Oxygen transport in the blood is carried primarily by red blood cells because they contain hemoglobin, a protein with iron-containing heme groups that reversibly bind oxygen. In the lungs, hemoglobin binds O2 to form oxyhemoglobin; as blood travels to tissues with lower oxygen and higher carbon dioxide, hemoglobin releases O2 to cells and picks up CO2 to be carried back to the lungs. Red blood cells are optimized for this task by having a biconcave shape and by lacking mitochondria, so they don’t consume the oxygen they transport. Plasma, leukocytes, and platelets have other roles—plasma is the fluid part carrying nutrients and wastes, leukocytes defend against infection, and platelets help with clotting—so they don’t primarily transport oxygen.

Oxygen transport in the blood is carried primarily by red blood cells because they contain hemoglobin, a protein with iron-containing heme groups that reversibly bind oxygen. In the lungs, hemoglobin binds O2 to form oxyhemoglobin; as blood travels to tissues with lower oxygen and higher carbon dioxide, hemoglobin releases O2 to cells and picks up CO2 to be carried back to the lungs. Red blood cells are optimized for this task by having a biconcave shape and by lacking mitochondria, so they don’t consume the oxygen they transport. Plasma, leukocytes, and platelets have other roles—plasma is the fluid part carrying nutrients and wastes, leukocytes defend against infection, and platelets help with clotting—so they don’t primarily transport oxygen.