Final answer:
The chloride shift maintains electrical neutrality by exchanging bicarbonate ions for chloride ions as carbon dioxide is transported in the blood, which allows for efficient carbon dioxide transport and release at the lungs. Correct option is B.
Step-by-step explanation:
The relationship between the chloride shift and the transport of carbon dioxide in the blood is fundamental to maintaining the acid-base balance and allowing for efficient gas exchange. During this process, carbon dioxide is converted into bicarbonate (HCO3-) within red blood cells by the enzyme carbonic anhydrase. To maintain electrical neutrality, the bicarbonate ion is exchanged for a chloride ion (Cl-) through the red blood cell membrane, a process known as the chloride shift. This exchange allows for the continued transport of carbon dioxide in the blood as bicarbonate, while hemoglobin frees up to transport oxygen.
In the lungs, the process is reversed. The bicarbonate ion enters red blood cells in exchange for chloride ions. The bicarbonate ion then combines with a hydrogen ion (released from hemoglobin upon oxygen binding) to form carbonic acid, which is converted back to carbon dioxide and water using carbonic anhydrase. Finally, the carbon dioxide is exhaled from the body.The majority of carbon dioxide molecules (85 percent) are carried as part of the bicarbonate buffer system. The bicarbonate ion is transported out of red blood cells in exchange for a chloride ion, a process known as the chloride shift. In the lungs, bicarbonate is transported back into red blood cells in exchange for chloride, allowing for the release of carbon dioxide.