Final answer:
Carbon dioxide is transported in the blood by dissolution, binding to hemoglobin, or as bicarbonate. Most CO2 is carried as bicarbonate. The process is regulated by the partial pressure of carbon dioxide, which affects respiratory rates and pH balance.
Step-by-step explanation:
The transport of carbon dioxide in the blood is a vital physiological process, essential for maintaining proper pH balance and gas levels within the body. Carbon dioxide is transported in the blood via three main mechanisms: as dissolved carbon dioxide, bound to proteins or hemoglobin, or converted into bicarbonate. Most of the carbon dioxide, approximately 90%, is transported as bicarbonate ions formed within erythrocytes. The enzyme carbonic anhydrase catalyzes the reaction of carbon dioxide with water to form carbonic acid, which dissociates into bicarbonate and hydrogen ions. This bicarbonate is then exchanged for chloride ions in a process known as the chloride shift.
At the pulmonary capillaries, the process is reversed, allowing carbon dioxide to be expelled from the body. Approximately 5 to 7 percent of carbon dioxide is dissolved directly in the plasma, whereas about 10 percent binds to hemoglobin to form carbaminohemoglobin. The partial pressure of carbon dioxide in blood plays a crucial role in determining its movement across the respiratory membrane, affecting both the rate of breathing and the body's pH balance.