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What do you understand from the term "digestion" ? |
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Answer» Digestive system: The system of organs responsible for getting food into and out of the body and for making use of food to keep the body healthy. The digestive system includes the salivary glands, mouth, esophagus, stomach, liver, gallbladder, pancreas, small intestine, colon, and rectum.hope it helps u Digestive system: The system of organs responsible for getting food into and out of the body and for making use of food to keep the body healthy. The digestive system includes the salivary glands, mouth, esophagus, stomach, liver, gallbladder, pancreas, small intestine, colon, and rectum. \tThe human digestive system consists of the alimentary canal and the associated glands.Alimentary canal\xa0\tThe alimentary canal begins with an anterior opening – the mouth, and it opens out posteriorly through the ****.\tThe mouth leads to the buccal cavity or oral cavity, which has a number of teeth and a muscular tongue and each tooth is embedded in a socket of jaw bone with a type of attachment called as\xa0thecodont.\tA set of temporary milk or deciduous teeth is replaced by a set of permanent or adult teeth, and the type of dentition is called\xa0diphyodont.\tAn adult human has 32 permanent teeth, which are of four different types\tincisors (I)\tcanine (C)\tpremolars (PM)\tand molars (M).\tArrangement of teeth in each half of the upper and lower jaw in the order I, C, PM, M is represented by a dental formula which in human is 2123/2123.\tThe tongue is a freely movable muscular organ attached to the floor of the oral cavity by the\xa0frenulum, and the upper surface of the tongue has small projections called\xa0papillae, some of which bear taste buds.\tThe oesophagus and the trachea open into the pharynx.\tA cartilaginous flap called\xa0epiglottis\xa0prevents the entry of food into the glottis, which is the opening of the wind pipe.\tThe oesophagus is a thin, long tube which extends posteriorly passing through the neck, thorax and diaphragm and leads to a ‘J’ shaped bag like structure called\xa0stomach.\tThe stomach has three major parts\ta cardiac portion into which the oesophagus opens\ta fundic region\ta pyloric portion which opens into the first part of small intestine.\tSmall intestine is distinguishable into three regions\ta ‘U’ shaped duodenum\ta long coiled middle portion jejunum\ta highly coiled ileum.\tThe opening of the stomach into the duodenum is guarded by the\xa0pyloric sphincter.\tIleum consists of\tcaecum\tcolon\t\xa0\tCaecum is a small blind sac from which a vestigial organ called\xa0vermiform appendix\tThe colon is divided into three parts\tan ascending\ta transverse\ta descending part.\tThe descending part opens into the\xa0rectum\xa0which opens out through the\xa0****.\tThe wall of alimentary canal from oesophagus to rectum possesses four layers\tSerosa\tmuscularis\tsub-mucosa\tSerosa is the outermost layer and is made up of a thin mesothelium and some connective tissues.\tMuscularis is formed by smooth muscles usually arranged into an inner circular and an outer longitudinal layer.\tThe submucosal layer is formed of loose connective tissues.\tMucosa is the innermost layer which forms\xa0rugae\xa0in the stomach and small finger-like foldings called\xa0villi\xa0in the small intestine.\tThe cells lining the villi produce numerous microscopic projections called\xa0microvilli\xa0giving a brush border appearance.\tVilli are supplied with a network of capillaries and a large lymph vessel called the\xa0lacteal.\tMucosal epithelium has\xa0goblet cells\xa0which secrete mucus that help in lubrication.\tMucosa forms gastric glands in the stomach\xa0crypts of Lieberkuhn\xa0in different parts of the alimentary canal. |
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