covered by a thin connective . . Histology of the Gut The wall of the alimentary canal from oesophagus to rectum consists of four layers (Figure . ) namely serosa, muscularis, sub-mucosa and mucosa.
The serosa (visceral peritoneum) is the outermost layer and is made up of thin squamous epithelium with some connective tissues. Muscularis is made of smooth circular and longitudinal muscle fibres with a network of nerve cells and parasympathetic nerve fibres which controls peristalsis. The submucosal layer is formed of loose connective tissue containing nerves, blood, lymph vessels and the sympathetic nerve fibres that control the secretions of intestinal juice. The innermost layer lining the lumen of the alimentary canal is the mucosa which secretes mucous.
. . Digestive Glands Digestive glands are exocrine glands which secrete biological catalysts called enzymes. The digestive glands associated with the alimentary canal are salivary glands, liver and pancreas.
Stomach wall has gastric glands that secrete gastric juice and the intestinal mucosa secretes intestinal juice. Figure . The layers of the alimentary canal Ascending colon I leocecal sphincter (valve) Cecum Vermiform appendix Anus I leum Anal canal Rectum Sigmoid colon Haustra Descending colon Transverse colon Figure . Large intestine XI Std Biology-Zoology Chapter- 3DURWLGV JODQG 6XEOLQJXDO JODQG 6XEPD[LOODU\ JODQG 6XEPDQGLEXODU JODQG :KDUWRQ¶VGXFW %DUWKROLQ¶VGXFW 6WHQVRQ¶VGXFW .
Stores glucose in the form of glycogen or disperses glucose into the blood stream with the help of pancreatic hormones . Stores fat soluble vitamins and iron . Detoxifies toxic substances. .
Involves in the synthesis of non- essential amino acids and urea. tissue sheath called the Glisson’s capsule . Liver cells (hepatic cells) secrete bile which is stored and concentrated in a thin muscular sac called the gall bladder. The duct of gall bladder (cystic duct) along with the hepatic duct from the liver forms the common bile duct.
The bile duct passes downwards and joins with the main pancreatic duct to form a common duct called hepato-pancreatic duct. The opening of the hepato-pancreatic duct into the duodenum is guarded by a sphincter called the sphincter of Oddi ( Figure. . ) .