The first (in animals) is eating and digesting food. Food is absorbed and broken down. This is done by physical breakdown (chewing and stomach churning), then chemical breakdown by enzymes and acids) The results are absorbed into the bloodstream.
The second process of is the chemical alteration of substances in the bloodstream by the liver. Many compounds needed by cells are done by this second process. Both the liver and cellular secretions can be very specific in their action. This second process is where the absorbed food reaches the cells via the liver.