When William was helping victims following a devastating earthquake in a region that was 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 that have been contaminated by fecal material from infected individuals. The toxin produced by chlorea bacteria causes Cl- channels in the luminal membrane of the intestinal cells to open, thereby increasing he secretion of Cl- from the cells into the intestinal tract lumen. By what mechanisms would Na and water be secreted into the lumen in conjunction with Cl- secretion? How does this secretary response account for the severe diarrhea that is characteristic of cholera?