The organisation of the is the digestive system is the same as in rabbits; it consists of the alimentory canal and the associated digestive glands ,the PANCREAS and LIVER .However , in contrast with the rabbit ,the digestive system of the man shows the following pecu larities ; 1 The mouth has three pairs of salivary glands ,i.e., a pair of parotid ,apair of sub-maxillary and apair of sub lingual glands . 2 . The mouth cavity has 32 teeth on both the jaw aand the dental formula of the man isI2/2,C1/1 ,PM2/2 ,P3/3 and the dental formula of the child is I2/2 ,C1/1 ,PM2/2, M0/0 witha total of 20 milk teeth .However ,molars erupt only in the adult . 3 The oesophagus is 20-30 cm long but the small intestine is about 7.5 m length and about 2.5cm on width . 4 The colon measures from 1.2 -1.5 m in length and and about 8cm in width .However the rectum is only 15cm long .5 . The liver ,divided into large right an small left lobes , weighs about 1.5kg .6 .The pancreas is whitish racemose gland. FOOD Any matter ,other than oxygen, that an animal takes into its body to make its part is called FOOD.It is important to animal and plant in the following respects ; 1; It is used as fuel to release energy during the respiration .The energy is required for various life activities . 2;It is used as building material to make new tissues and thus cause growth . 3; It is used as repair material for broken tissues and cells .4; It provides material to form certain essential substance and close [e.g . hormones ,enzymes ,etc ] in the body . FOOD COMPONENT The food that animal eats consists of organic and inorganic substances .These substances are called food components or food constituents or food stuffs. These include carbohydrates, lipids,proteins,vitamins ,mineral salt and water .The former four are organic constituents and the latter two are inorganic constituents .Let us learn about these . 1.Carbohydrates .These are compound of carbon , hydrogen and oxygen .The ratio of hydrogen and oxygen in them is as in water , that is 2:1 . These compound usually make the bulk of the food and are chif sources of energy in the body , one gram of a carbohydrate yields 4.1 calories .The carbohydrates include sugars ,starch , glycogen and cellulose . 2.These include fats and oils .Like carbohydrates ,these are also made of carbon , hydrogen and oxygen but the ratio of hydrogen to oxygen in them is not as in water ; in fact , the oxygen is much lesser in them as compared to carbohydrates .Like carbohydrates , these are also used for producing energy in the body and these produce more energy than carbohydrates. 3.Proteins ;These are large molecules of carbon, hydrogen and oxygen and nitrogen .The last one is essential constituent of the proteins hence the proteins are called nitrogenous compound .Some proteins also contain either sulphur or phos phorous or iron . Each proteins is made of smaller simple units called amino acids .The haemoglobin is a large ptotein molecule .Albumin , globulin ,fibrinogen etc., are other example of protein
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