The large intestine

The small intestine joins a wider tube, the large intestine (large because it is wider than the small intestine) at the cecum (ileocecal junction), in the right lower abdominal cavity. The cecum is a saclike pouch with only one opening; the cavity in which the large intestine begins and into which the ileum opens. The cecum absorbs water and salt from undigested food. From the lower end of the cecum extends a 10 cm long blind ended tube, the appendix, which, just like the cecum, has no major function in the digestive process.
The approximately 1.5 meters long large intestine or colon is responsible for absorption of minerals, chemicals, nutrients and water from the digested food, and excretion of solid waste material. Similarly to other parts of the digestive tract, the walls of the large intestine are muscular, and contract to move material along its length. Unlike the small intestine, the large intestine does not produce digestive enzymes. The pH in the colon varies between 5.5 and 7 (neutral or slightly acidic). Chemical digestion is completed in the small intestine before the chyme reaches the large intestine. Substances which have not been absorbed in the small intestine enter the large intestine in the form of liquid and fiber. As the chyme moves through the large intestine, the remaining nutrients are absorbed and water is removed, while the chyme is mixed with mucus and bacteria, and becomes feces.
The large intestine consists of the colon, rectum, and anal canal. The colon consists of ascending, transverse, descending, and sigmoid portions. The ascending colon extends from the cecum upward, along the right abdominal wall, to the under surface of the right lobe of the liver, where it bends abruptly forward and to the left (this bend is called the right colic flexure). This is where the transverse colon, the longest part of the colon starts. It passes across the abdomen with a downward convexity, curves sharply beneath the lower end of the spleen (this curve is the left colic or splenic flexure) into the descending colon. The descending colon passes downward along the left abdominal wall to the pelvic region (the lower part of the abdomen located between the hip bones). The colon then forms an approximately 40 cm long loop, the sigmoid colon, which normally lies within the pelvis. The remaining materials from the digested food move from the colon into the rectum. The rectum is a short (about 12 cm long) muscular tube, that acts as a temporary storage facility for feces.
It then bends sharply backward into the anal canal.
The last 2 to 3 cm of the digestive tract is the anal canal, which continues from the rectum and opens to the outside at the anus. The anus is the opening where stool exits the body through a ring of muscles, the anal sphincter. The sphincter keeps the anus closed as stool collects in the rectum. Eventually the pressure on the rectum wall causes the anal sphincter to relax, allowing stool to pass out of the body through the anus.