The large intestine, which is about 5 feet long and 2.5 centimeters in diameter, extends from the ileum to the anus. It consists of the cecum, colon, rectum, and anal canal. 
The cecum is the first part of the large intestine and is where the large and small intestines meet at the ileocecal junction. The ileocecal junction or valve prevents backing up of fecal matter (stool) into the small intestine. Attached to the cecum is a tube about 8-9cm. long called the appendix. The appendix has no known use in digestive processes.
The colon consists of four parts: the ascending colon, the transverse colon, the descending colon, and the sigmoid colon.
The rectum is a straight, muscular tube that begins at the end of the sigmoid colon and ends at the anal canal.
The anal canal is the last 2-3 cm of the digestive tract. The opening of the anal canal to the outside is called the anus.
Functions of the large intestine:
The major functions of the large intestine is to absorb water, nutrients, and salts from the partially digested food that enters from the small intestine. Two pints of liquid matter enter the colon from the small intestine each day. Stool volume is a third of a pint. The difference between the amount of fluid entering the colon from the small intestine and the amount of stool in the colon is what the colon absorbs each day.
Colon motility (the contraction of the colon muscles and the movement of its contents) is controlled by nerves, hormones, and impulses in the colon muscles. These contractions move the contents inside the colon toward the rectum. During this passage, water and nutrients are absorbed into the body, and what is left over is stool.
A few times each day contractions push the stool down the colon, resulting in a bowel movement. However, if the muscles of the colon, sphincters, and pelvis do not contract in the right way, the contents inside the colon do not move correctly, resulting in abdominal pain, cramps, constipation, a sense of incomplete stool movement, or diarrhea.
Image Credit: NIDDK Image Library. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). National Institutes of Health.
Page Last Revised: August 26, 2011
The cecum is the first part of the large intestine and is where the large and small intestines meet at the ileocecal junction. The ileocecal junction or valve prevents backing up of fecal matter (stool) into the small intestine. Attached to the cecum is a tube about 8-9cm. long called the appendix. The appendix has no known use in digestive processes.
The colon consists of four parts: the ascending colon, the transverse colon, the descending colon, and the sigmoid colon.
The rectum is a straight, muscular tube that begins at the end of the sigmoid colon and ends at the anal canal.
The anal canal is the last 2-3 cm of the digestive tract. The opening of the anal canal to the outside is called the anus.
Functions of the large intestine:
The major functions of the large intestine is to absorb water, nutrients, and salts from the partially digested food that enters from the small intestine. Two pints of liquid matter enter the colon from the small intestine each day. Stool volume is a third of a pint. The difference between the amount of fluid entering the colon from the small intestine and the amount of stool in the colon is what the colon absorbs each day.
Colon motility (the contraction of the colon muscles and the movement of its contents) is controlled by nerves, hormones, and impulses in the colon muscles. These contractions move the contents inside the colon toward the rectum. During this passage, water and nutrients are absorbed into the body, and what is left over is stool.
A few times each day contractions push the stool down the colon, resulting in a bowel movement. However, if the muscles of the colon, sphincters, and pelvis do not contract in the right way, the contents inside the colon do not move correctly, resulting in abdominal pain, cramps, constipation, a sense of incomplete stool movement, or diarrhea.
Image Credit: NIDDK Image Library. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). National Institutes of Health.
Page Last Revised: August 26, 2011
