At its most basic level, diarrhoea results from an imbalance of absorption and secretion of ions and solute across the gut epithelium, followed by the movement of water in an attempt to restore the appropriate ion concentrations. Often, this imbalance is caused by the presence of bacteria that secrete toxins that disturb the organization of the epithelium. NIH
The gut, known as the enteric nervous system, is located in sheaths of tissue lining the esophagus, stomach, small intestine and colon, and plays a key role in human emotions. But few know the enteric nervous system exists, and therefore gut health is often overlooked. Symptoms from the two brains can get confused....
The intestine absorbs nutrients while simultaneously forming a barrier to noxious substances and bacteria. Along its 7 metre length, the human intestine displays regional specialization, which is further marked by the presence of distinct cell types in different areas.
Osmotic laxatives, such as Fleet Phospho-Soda, Milk of Magnesia, or Miralax, and nonabsorbable sugars (such as lactulose or sorbitol), hold fluids in the intestine. More info.