The inner lining of the small intestine is composed of up to five million tiny, fingerlike projections called villa. The villa increase the rate of absorption of nutrients into the bloodstream by greatly increasing the surface area of the small intestine. Absorption and elimination in the large intestine The large intestine is wider and heavier than the small intestine. However, it is much shorter—only about 5 feet (1.5 meters) long. It rises up on the right side of the body (the ascending colon), crosses over to the other side underneath the stomach (the transverse colon), descends on the left side, (the descending colon), then forms an s-shape (the sigmoid colon) before reaching the rectum and anus. The muscular rectum, about 6 inches (16 centimeters) long, expels feces (stool) through the anus, which has a large muscular sphincter that controls the passage of waste matter. The large intestine removes water from the waste products of digestion and returns some of it to the bloodstream. Fecal matter contains undigested food, bacteria, and cells from the walls of the digestive tract. Millions of bacteria in the large intestine help to produce certain B vitamins and vitamin K. These vitamins are absorbed into the bloodstream along and the water. Disorders of the digestive system Among the several disorders that affect the digestive system are esophagi is (heartburn) and ulcers. Esophagi is an inflammation of the esophagus caused by gastric acids flowing back into the esophagus. Mild cases of this condition are usually treated and commercial antacids. Stomach ulcers are sores that form in the lining of the stomach. They may vary in size from a small sore to a deep cavity. Ulcers that form in the lining of the stomach and the duodenum are called peptic ulcers because they need stomach acid and the enzyme pepsin to form. Duodenal ulcers are the most common type.