The bacterium Vibrio cholerae causes the disease cholera. Infected people have such severe diarrhea, that they may lose as much as 20 L of fluid in a 24 hour period. The bacterium enters the body when a person drinks contaminated water, then attaches to the intestinal lining. During its metabolic activities, it secretes a compound that is toxic to cells of the lining, and they start secreting chloride ions. Sodium ions follow the chloride ions into the fluid in the intestines. Explain how this sequence of events causes the massive fluid losses.