What is the primary function of the large intestine?

The primary function of the large intestine is to reabsorb water and eliminate waste. As food residues pass through the large intestine, the body absorbs much of the remaining water and electrolytes from this material, which is crucial for maintaining fluid balance and overall hydration. This process transforms the liquid chyme from the small intestine into more solid feces as water is reabsorbed. Additionally, the large intestine plays a key role in the formation and storage of feces until they are excreted from the body. The elimination of waste is essential for the expulsion of substances that are no longer useful to the body and can be harmful if retained.

In contrast, breaking down proteins is primarily the function of the stomach and small intestine, while nutrient absorption predominantly occurs in the small intestine. Producing insulin is a function of the pancreas, not the large intestine. Hence, the focus on water reabsorption and waste elimination accurately reflects the primary roles of the large intestine.