 Now, we talk about the processes of nutrition includes acquiring energy, various strategies as we talked about previously, various strategies of acquiring food by mouth parts, by behavior or may be through sunlight or something, but the organisms particularly animals we are more concerned in this course with animals, they have to digest their food, we divide this process in few steps, we call them ingestion, taking the food in, the next step is digestion, digestion means breaking the food into smaller parts, then comes absorption, absorbing those smaller parts, then comes assimilation that is making those broken parts or very very small pieces, the digested food part of the body or convert these into energy and utilizing these for various functions of the body or may be for making different structures of the body, then comes at the end, elimination, removing the undigested parts of the food from the body, we call it elimination, so the whole process of the nutrition and digestion is ingestion, digestion, absorption, assimilation and elimination, after acquiring food that is having some food in front, organism have to ingest that food, take that food inside the mouth, then next step comes the digestion, when the food comes inside the digestive tract of the organism, then organism have to break it into smaller pieces, we call this process digestion, when the food is digested, broken into smaller parts, then it have to be absorbed by the transport system of the organism, that is the blood circulatory system, it have to go or absorbed by the blood through the digestive system, then it have to be distributed throughout the body to be assimilated and the remaining part which is not digested which is undigestible have to be eliminated from the body, we take the example of the human digestive system to describe and explain all of these processes, human beings as we know we are the omnivores, we eat vegetables, some of us are totally vegetarian, some of us are mainly meat eaters, but we take some vegetables, but most of us eats both things or maybe the combination of these, we are omnivores, we can eat both, if we look at our teeth, our teeth have all the four types, we have incisors, our front teeth, we have canines, all the four on sides, then comes our premolar, premolars and the molars which we call as so we have all the four kinds of teeth, because we have to take all types of food, digestive system also adapt according to the nature of the food present, available to an organism, human being is available with almost all types of foods, now we talk about the basic components of human digestive system, the human digestive system consist of an elementary canal which starts from mouth to anus, then it is associated with certain accessory glands, for example, liver, pancreas which over there some secretions inside the digestive tract to help in the digestion of food, we start from the elementary canal, the elementary canal of human beings is a very long tube, hollow straight, hollow tube which is when it reaches at intestine, it is highly convoluted of course, because intestine is very long, the various parts of human digestive tube or the elementary canal are the oral cavity, the pharynx, esophagus, stomach, intestines, small intestine and the large intestine and the last part the rectum and the anus and then comes the accessory glands, liver and pancreas which are associated with the digestive system, but they are very important part of the digestive system, because they have to pour certain secretions which have to digest certain parts of the foods without them we cannot digest some parts of the food or we may not detoxify our internal organs.