As bicarbonate ions (HCO3-) diffuse out of the red blood cell, chloride ions (Cl-) from the plasma diffuse into the cell, thus maintaining the electrical balance between ions. This exchange of ions is called the chloride shift.

least 70% of the carbon dioxide transported in the blood is carried in this form.

As the bicarbonate ions leave the red blood cells and enter the plasma, chloride ions, which also have negative charges, are repelled electrically, and they move from the plasma into the red blood cells. This exchange in position of the two negatively charged ions, shown in figure 19.42, maintains the ionic balance between the red blood cells and the plasma. It is termed the chloride shift.

Shier-Butler-Lewis: I V. Absorption and I 19. Respiratory System I I © The McGraw-Hill

Human Anatomy and Excretion Companies, 2001

Physiology, Ninth Edition

Alveolar wall


Essentials of Human Physiology

Essentials of Human Physiology

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