Man is an active being. In order to carry out his activity, he has to get energy; this energy is secured by the food he takes. Food is converted into energy, through digestion and assimilation. This process is carried out by the digestive system.
The digestive system of cockroach consists of alimentary canal and digestive glands. One of the peculiarity of the digestive system is that the system although mainly involved in the process of digestion, it also takes part in excretion being associated with Malpighian tubules which open into the alimentary canal at the junction of midgut and hind gut.
The essential functions of Digestive Glands are:- In man there are three pairs of salivary glands (sub maxillary, sublingual, and parotid) which secrete saliva. Saliva contains an enzyme called salivary amylase which breaks down starch (complex substance) of the food into maltose (a simpler sugar).
Food gives us the energy to work and play. To be of use to the body, the food we eat has to be digested properly. We eat many different kinds of food in the course of a day. The digestive system breaks down this food into smaller parts that can be easily absorbed by the body. This process is called digestion.