The large intestine is the organ that follows the small gut but is the last part of the digestive tract before the waste leaves the body.
The small intestine is on average about five feet long. It is composed of four distinct structural parts; the cecum, colon, and anus.
The cecum is the part of the large intestine that comes first. It is separated into three parts. The taeniae coli are three bands of smooth muscle. The haustra are bulges caused by contractions of the taeniae coli. While the last part of the Cecum is the small fat accumulations located on the viscera called epiploic appendages.
The colon is the part of the large intestine where colonic bacteria create vitamins to be absorbed. It is also the part that stores fecal matter and compacts feces before it is sent through the anus.
The large intestine is filled with many types of bacteria (i.e. bacterial flora, gut flora, etc). Luckily, a mucus-like layer defends the intestine from colonic commensal bacterium attacks.
The large intestine aids in digestion before waste leaves the body. It is absorbing the last of the liquids and nutrients before sending the rest on its way to the rectum. It also absorbs nutrients that its bacteria creates in order to maintain adequate blood coagulation.
Image Caption: Diagram of the Human Intestine drawn by Duncan Lock. Credit: Connormah/Wikipedia