Large Intestine and Anal Canal

Structure of Large Intestine

Hey all AIPMT Biology Aspirants, check out the next topic Notes of Large Intestine and Anal Canal.

Large intestine

  • Large intestine is the terminal portion of the Gastro-intestinal tract.
  • It extends from Ileum to the Anus. It consists of Caecum, Colon and Rectum.
  • The opening from the ileum into the large intestine is guarded by a fold of mucous membrane called the Ileocaecal sphincter/valve, which allows materials from the small intestine to pass into the large intestine.
  • Hanging inferior to the ileocecal valve is the Caecum. Caecum is a small blind sac which hosts some symbiotic micro-organisms. Attached to the caecum is a twisted, narrow finger-like projection, measuring about 8 cm in length, called as Appendix or Vermiform appendix,which is a vestigial organ.The caecum opens into the long tube colon.
  • The colon is divided into – Ascending, Transverse and Descending and Sigmoid Colon.
  • Ascending colon ascends on the right side of the abdomen, then turns left and continues across the abdomen to the left side as the transverse colon. It again turns and descends as descending colon.
  • Sigmoid colon is the curved last part of colon which is connected to the rectum.
  • Rectum lies anterior to the sacrum and coccyx and opens into anal canal.
  • Overall functions of the large intestine are the completion of absorption, production of certain vitamins, formation of feces, and the expulsion of feces from the body.
Structure of Large Intestine

Structure of Large Intestine

Anal canal

  • Anal canal is considered as terminal parts of large intestine.
  • The opening of the anal canal to the exterior, called the Anus, is guarded by an Internal anal sphincter of smooth muscle (involuntary) and an External anal sphincter of skeletal muscle (voluntary). Normally these sphincters keep the anus closed except during the elimination of feces.
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