Answer:
In the digestive system of mammals, two groups of food that are reabsorbed without undergoing digestion are water and electrolytes. These substances are absorbed directly from the small intestine into the bloodstream, where they are transported to the cells of the body to be used for various metabolic processes.
Water and electrolytes are essential for the proper functioning of the body, as they help to maintain hydration, regulate body temperature, and support the transmission of nerve impulses. In the small intestine, they are absorbed through the walls of the blood vessels and pass into the bloodstream, where they are distributed to the cells and tissues of the body.
Because they are not digested, water and electrolytes do not provide any nutritional value to the body. However, they are still important for maintaining overall health and wellbeing.