 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 duisions. The second region is called the head gut, which is specialized for the intake or ingestion of food. It comprises of buccal cavity and pharynx. The second region 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. In the mid-gut, there is a small intestine, which is divided into different small components, which are called duodenum, gjunum and helium. The mid-gut functions are to complete the digestion of food and absorb the products of digestion. The fourth division of digestive tract is the hind-gut, which comprises of large intestine. Large intestine k bimukhli components that is colon, cecum, rectum and anus, which collectively form the hind-gut. There are two major functions of hind-gut, absorption of water and electrolytes, and the second is the removal of undigested waste. Dear students, we saw that mammalian digestive tract is divided into different regions. These regions are specialized to carry out specific functions. This is called regional specialization. Regional specialization ki vajah se mukhli digestive actions ek stepwise fashion mein hote hai, misal ke torpah, mechanical treatment, microbial treatment, enzymatic digestion, absorption or waste storage, ye ek sequence mein mukhli regions of the digestive tract mein hote hai. 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, ek elementary canal ke saath kuch accessory glands bhi associated hote hai, which secrete the digestive juices through their ducts. These accessory glands include three pairs of slivery glands, gastric glands, pancreas, liver and gallbladder.