Digestive System in Mammals

Digestive System in Mammals

Digestive System in Mammals

The process of breaking down of complex food into simpler forms with the help of various enzymes is known as digestion. The system that deals with with this process of digestion is known as digestive system.
Digestive system in Mammals can be studied under  following  two headings:-

  1. Alimentary Canal
  2. Digestive Glands

Digestive System in Mammals

  1. Alimentary Canal
    1. Mouth and Buccal Cavity
      Mouth in mammals is an anterior wide opening bounded by fleshy upper and lower lips. Mouth is immediately followed by a wide buccal cavity which usually consist of structures like teeth and tongue. Teeth are absent in some mammals like whales, pangolins, spiny ant eaters etc. Teeth in mammals are the thecodont, heterodont and diphyodont type. In herbivorous canine teeth are absent while in carnivors canine teeth are much elongated and pointed. In them pre-molar and molars also have sharp edges.

      Tongue is a muscular organ present at the base of buccal cavity. It is a short and non protrusible in most mammals except in bats and spiny ant eaters where it is long and protrusible.
    2. Pharynx
      Pharynx in mammals is also short as found in other vertebrates and it simply leads towards oesophagus.
    3. Oesophagus
      It is narrow and muscular tube like organ which helps to conduct the food towards the stomach. In rodents and herbivors, the inner lining of oesophagus is highly keratinized.
    4. Stomach
      Stomach in mammals is variously modified. In most of the mammals, it is a sac like organ, differentiated into anterior cardia, middle body and posterior pylorous. In ruminants(cattle) stomach consist of four well developed chambers which are rumen, reticulum, omassum and abomassum. The first three chambers simply help in storing the food while the fourth chamber; abomassum consist of gastric glands and help in digestion of food.
    5. Small Intestine
      It is narrow, highly coiled and elongated structure where the digestion and absorption of food take place. It is separated from stomach by a narrow pyloric constriction. It is divisible into three parts namely duodenum, jejunum and ileum. Small intestine in herbivors is comparatively longer than that of carnivors as chemical digestion is comparatively slow in herbivors.
    6. Large Intestine
      Large intestine in them is a wide tubular organ differentiated into anterior caecum, middle colon and posterior rectum. In herbivors, caecum is more developed and consist of an elongated appendix at its tips while at carnivors and in primates, caecum is comparatively small and it has vestigial appendix. Large intestine basically helps in absorption of water and temporary storage of undigested food.
    7. Anus
      Large intestine in mammals opens outside through the anus, through which undigested food materials are passed outside. All the mammals have anus except for monotremes (Eg. Platypus) which have cloacal aperture.
  2. Digestive Glands
    • Liver
      Liver in mammals is large,wide and flattened gland. It is multi-lobed(consist of more than three lobes) and secrete bile for emulsification of fats. Liver in most mammals is provided with gall bladder but absent in mammals like whales, rodents, zebra, giraffe etc.
    1. Pancreas
      Pancreas in mammals is a compact and yellowish coloured organ present in the either in the loops of duodenum or in between stomach and duodenum. It secrete pancreatic juice containing various enzymes to digest the food.
    2. Salivary Glands
      Buccal cavity of mammals has well developed salivary glands which secrete saliva containing an enzyme called salivary amylase(Ptylin) to digest carbohydrate component of food.

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