In human respiratory physiology, how is the majority of carbon dioxide transported from active body tissues back to the lungs for elimination?

💡 Solution & Explanation

Approximately seventy percent of carbon dioxide produced by cellular respiration is transported in the blood in the form of bicarbonate ions dissolved in plasma, facilitated by the enzyme carbonic anhydrase within red blood cells. While small amounts travel dissolved in plasma or bound to hemoglobin as carbaminohemoglobin, bicarbonate transport is the primary buffering mechanism. Chloride shift maintains electrical neutrality as bicarbonate ions move out of red blood cells into the plasma in exchange for chloride ions.