Large Intestine and Anus

The large intestine begins where the ileum opens into it and is about 1.5 metres long — shorter but wider in diameter than the small intestine. It consists of three parts:

• Caecum: a small, blind sac, about 6 cm long, at the junction of the ileum and the colon. It hosts symbiotic micro-organisms, and gives rise to a worm-like, elongated vermiform appendix, which is vestigial (functionless) in humans but functional in herbivorous animals, helping them digest cellulose.
• Colon: a tube-like organ with three parts — ascending colon, transverse colon and descending colon — internally lined by mucosal cells.
• Rectum: the posterior-most region of the large intestine, which temporarily stores the undigested waste (faeces) until it is expelled. …