What is the main function of the cecum?

The cecum is the first section of the large intestine and is vital to the digestive system. 

Its primary function is to absorb fluids and salts from partially digested food as it exits the small intestine. This reabsorption aids in the concentration of undigested food matter and prevents dehydration. 

The cecum also receives an undigested food material, bacteria, and mucus and begins to ferment it, which aids in the breakdown of the food and promotes the growth of beneficial gut bacteria. 

These bacteria are essential for digestive and overall health. The cecum then transports the remaining undigested food from the large intestine for further processing.

This fluid and salt absorption by the cecum is important for maintaining fluid and electrolyte balance in the body, as well as for forming semi-solid faeces that are stored in the rectum until they are eliminated from the body through the anus.