Hemoglobin is important for the transport of which gases?

Hemoglobin is the iron-containing protein found within red blood cells that is responsible for the transport of respiratory gases. Its primary function is carrying oxygen from the lungs to the body's tissues: oxygen binds to the iron-containing heme groups of hemoglobin in the pulmonary capillaries, forming oxyhemoglobin. Hemoglobin also plays a critical role in carbon dioxide transport, carrying approximately 20 to 25 percent of total carbon dioxide as carbaminohemoglobin — carbon dioxide binds to the globin protein portion — while facilitating the conversion of the remainder into bicarbonate. This bidirectional gas transport is essential to maintaining tissue oxygenation and acid-base balance. Hydrogen is not transported by hemoglobin in the same direct way, though hemoglobin does act as a buffer for hydrogen ions as part of its contribution to acid-base regulation. Nitrogen is largely inert at normal atmospheric pressures and is not transported by hemoglobin under physiological conditions. Students sometimes confuse the role of hemoglobin with that of plasma proteins or confuse carbon dioxide transport with nitrogen. Remembering that hemoglobin is the key molecule for both oxygen delivery and carbon dioxide return to the lungs is central to understanding respiratory physiology.