[Gastroenterology] The large intestine

Organ system: The digestive system

The large intestine plays a role in digestion, stool formation, and water reabsorption.

Reabsorption of water

When digested matter reaches the large intestine it has already lost a lot of water and nutrients. Along the path from the large intestine to the anus it will lose a lot more water. This allows faeces to form with the correct consistency. Too much water removal and the faeces become hard, causing constipation. Too little water removal and the faeces remain soft, causing diarrhea and dehydration. 

 

The microbiome

The large intestine is a habitat for an enormous number of micro-organisms. This is not a pathological contamination, but it is more similar to a symbiotic relationship. It is a healthy and natural feature of the human body. These organisms have evolved to metabolise nutrients which pass through our intestines, releasing usable energy for them, and producing usable nutrients for us. A large volume of evidence has accumulated over the years to suggest that the microbiome influences obesity, diabetes, and even mood.