which the oesophagus opens a fundic portion and a pyloric portion that opens into the duodenum. The opening of the stomach into the duodenum is guarded by the pyloric sphincter. It periodically allows partially digested food to enter the duodenum and also prevents regurgitation of food. The inner wall of stomach has many folds called gastric rugae which unfolds to accommodate a large meal.
The small intestine assists in the final digestion and absorption of food. It is the longest part of the alimentary canal and has three regions, a ‘U’ shaped duodenum (25cm long), a long coiled middle portion jejunum ( .4m long) and a highly coiled ileum ( .5m long). The wall of the duodenum has Brunner’s glands which secrete mucus and enzymes. Ileum is the longest part of the small intestine and opens into the caecum of the large intestine.
The ileal mucosa has numerous vascular projections called villi which are 6DOLYDU\ JODQGV 2UDOFDYLW\ 3KDU\Q[ 2HVRSKDJXV /LYHU *DOO EODGGHU 3DQFUHDV &DUGLDF 6SKLQFWHU \ORULF 6SKLQFWHU 6WRPDFK 6WRPDFK 'XRGHQXP RIVPDOO LQWHVWLQH 0RXWK 2HVRSKDJXV *DOO EODGGHU /LYHU 3DQFUHDV $QXV $QXV $VFKHPDWLFGLDJUDPRI WKHKXPDQGLJHVWLYHV\VWHP 5HFWXP 5HFWXP /DUJH LQWHVWLQH /DUJH LQWHVWLQH 6PDOO LQWHVWLQH 6PDOO LQWHVWLQH 6DOLYDU\ JODQGV $SSHQGL[ /DVW SRUWLRQ RIVPDOO LQWHVWLQH +DXVWUD $VFHQGLQJ SRUWLRQRI ODUJH LQWHVWQH &HFXP OHRFHFDO YDOYH Figure . The Human Digestive System XI Std Biology-Zoology Chapter- The large intestine consists of caecum, colon and rectum. The caecum is a small blind pouch like structure that opens into the colon and it possesses a narrow finger like tubular projection called vermiform appendix . Both caecum and vermiform appendix are large in herbivorous animal and act as an important site for cellulose digestion with the help of symbiotic bacteria.
The colon is divided into four regions – an ascending, a transverse, a descending part and a sigmoid colon. The colon is lined by dilations called haustra (singular – haustrum) (Figure. . ).
The “S” shaped sigmoid colon (pelvic colon) opens into the rectum. Rectum is concerned with temporary storage of faeces. The rectum open out through the anus. The anus is guarded by two anal sphincter muscles.
The anal mucosa