That is, the process by which large complex nutrient molecules are broken down into simpler molecules capable of being used by the organism for food. The alimentary canal is a long winding tube with various enlarged sacs, beginning with the mouth and ending at the anus. Food undergoes complex mechanical and chemical changes as it moves through the alimentary canal or tube. The Mouth is the initial opening of the alimentary canal. The moistening also makes the food easier to swallow.
Mastication is more complex in herbivores than in carnivores.
It is the relative difficulty of digestion of cellulose. One pass and the wolf gets its nutrition, but to break down the cellulose takes more work, by the cow and the rumen microflora. The pharynx is a short, funnel shaped muscular sac between the mouth and esophagus. It is part of the digestive AND respiratory tracts. The esophagus is muscular tube that connects the pharynx to the stomach.