 Dear students, in this topic we shall discuss the structure of a generalized elementary canal. An elementary canal has a tubular organization. This tube extends between two openings, mouth and anus. We can take the mammalian digestive tract as a representative example of an elementary canal which can be compared to all other animals. The mammalian digestive tract has four major divisions. First division is called the head gut which is specialized for the intake or intake or ingestion of food. It comprises of buccal cavity and pharynx. The second division of elementary canal is the fore gut. It has specialized regions to conduct, store and partially digest the food. It includes asophagus for conduction, stomach for storage. In some animals crop is also used for temporary storage of food while stomach stores the food as well as partially digest the food. The third major division of mammalian digestive tract is the mid-gut. The mid-gut has small intestine. Small intestine is a large part which is divided into different small components which are called duodenum, gjunum and elium. The major function of mid-gut is to complete the digestion of food and absorb products of digestion. The fourth division of digestive tract is the hind gut which comprises of large intestine. There are also large intestine components that is colon, cecum, rectum and anus which collectively form the hind gut. There are two major functions of hind gut. One is absorption of water and electrolytes and the other is defecation that is removal of undigested waste. Dear students, we have seen that mammalian digestive tract is divided into different regions. All these regions are specialized to carry out specific functions. This is called regional specialization. Due to regional specialization, different digestive actions take place in a stepwise fashion. For example, mechanical treatment, microbial treatment, enzymatic digestion, absorption or waste storage are in different regions of the digestive tract. Regional specialization also permits the maintenance of acidic and alkaline pH at the same time in different parts of the elementary canal. This maintenance of different types of or different levels of pH is necessary for various enzymatic reactions. Dear students, with an elementary canal, there are some acessory glands also associated which secrete the digestive juices through their ducts. These acessory glands include three pairs of sliver glands, gastric glands, pancreas, liver and gallbladder.