Chapter 3, Problem 1ACR

When William H. was helping victims after a devastating earthquake in a region not prepared to swiftly set up adequate temporary shelter, he developed severe diarrhea. He was diagnosed as having cholera, a disease transmitted through unsanitary water supplies contaminated by fecal material from infected indiv iduals. The toxin produced by cholera bacteria causes ${\text{Cl}}^{\text{-}}$ channels in the lurninal membranes of the intestinal cells to stay open, thereby increasing the secretion of ${\text{Cl}}^{\text{-}}$ from the cells into the intestinal tract lumen. By what mechanisms would ${\text{Na}}^{\text{+}}$ and water be secreted into the lumen in conjunction with ${\text{Cl}}^{\text{-}}$ secretion? How does this secretory response account for the severe diarrhea that is characteristic of cholera?