Anatomy of Digestion- Part Two
It is a blind ended tube that develops embryologically. It is connected to cecum, just near the junction of the small intestine and the large intestine.
The cecum is the commencing part of large intestine. It is appeared like a pouch that connects the ileum with the ascending colon of the the large intestine. Ileocecal valve separates the ileum and cecum.
It is the last portion of the digestive tract. It is five feet in length with variable diameter. It is the place where the water and salts are extracted from the solid wastes before they are eliminated. Large intestine comprises of
is divided into four sections:
the ascending colon, the transverse colon, the descending colon and the sigmoid colon.
From ileum to anus the large intestine is one-fifth of the length of digestive canal. It appears different than small intestine by the sacculated appearance.
is about 25 cm long. It is extends form cecum area to the hepatic flexure. In the ascending colon the solid matter ascends for the absorption of water and essential minerals, hence it called ascending colon. Parasympathetic fibers of the vagus nerves supply the ascending colon and ileocolic artery and right colic artery are the blood suppliers of this part of colon.
extends from hepatic flexure to the spleanic flexure. It is encased in peritoneum and is therefore more mobile compared to other colons. The transverse colon hangs off the stomach and is attached to the stomach by the band of tissue called the greater omentum. Here the contents in the colon become more and more solid in order to form feces. Middle colic artery and a branch of mesenteric artery supply the blood to transverse colon.
begins at spleanic flexure and ends in the beginning of the sigmoid colon. Here the flow of the matter is descending hence the name descending colon. It is located in retro-peritoneal position and the main function of the descending colon is to store the solid matter that will be emptied into the rectum. Left colic artery supplies the descending colon.
is the continuation of the descending colon which joins rectum. The sigmoid means S-shaped structure of the colon. The main function is to move the stool in the rectum. Superior rectal artery supplies the sigmoid colon.
It is the continuation of sigmoid colon which is the final straight portion of the large intestine. It terminates in the anus. It measures about 12 cm and looks dilated at its termination to form rectal ampulla above the anus.
The anus is the last part of digestive tract. It is the opening from which the feces are expelled out to the environment. Feces is unwanted semi-solid waste matter that is formed after completion of the process of digestion. Interior and exterior sphincters control the expelling of feces from the anus.