The digestive tract consists of a group of hollow organs, including the mouth, esophagus, stomach, small intestine, large intestine, rectum and anus, which allow the flow of food particles through the body. The complete digestive system also includes solid organs, including the liver and pancreas, that produce digestive enzymes. The entire system together functions to break down food particles into smaller molecules the body absorbs and carries to the cells for use. Many conditions and diseases cause digestive difficulties by interfering with the ability of the digestive system to produce digestive enzymes, move contents or absorb the nutrients.
Celiac Disease
Celiac disease describes a digestive disorder characterized by the inability to tolerate gluten—a protein found in wheat, rye and barley. The small intestine functions to break down food particles as well as absorb the nutrients into the bloodstream. The lining of the small intestine contains folds and tiny projections known as villi that function to increase the absorptive surface area to roughly 250 square meters, according to Colorado State University.
In patients with celiac disease, the presence of gluten triggers the immune system to react, causing damage to the villi. As villi become damaged, the body cannot absorb nutrients effectively, leading to symptoms include bloating, gas, abdominal pain, diarrhea, constipation, unexplained weight loss and fatigue. These can lead to long-term complications such as anemia, bone or joint pain, vitamin K deficiency, delayed growth, infertility and miscarriages, as described by the Celiac Disease Foundation.
Lactose Intolerance
Lactose intolerance, the inability to digest a specific type of sugar known as lactose, describes a digestive difficulty that occurs when patients ingest milk products. Unlike celiac disease, lactose intolerance does not occur due to an immune system response. Patients with lactose intolerance fail to produce enough of the enzyme known as lactase, which functions to break down lactose into simple sugars the body can absorb.
Lactose intolerance produces symptoms similar to other digestive difficulties, including abdominal pain, abdominal bloating, gas and diarrhea. These symptoms typically occur 30 minutes to 2 hours after the ingestion of milk products, according to the National Digestive Diseases Information Clearinghouse.
Irritable Bowel Syndrome
Irritable bowel syndrome is a digestive disorder that affects the large intestine, which includes the colon. Although the exact cause of the disease remains unknown, doctors do know that it occurs when the layers of muscles lining the large intestine fail to contract and relax normally. The muscles lining the digestive tract normally contract and relax rhythmically to keep the food contents moving through the system.
In those with irritable bowel syndrome, the muscles contract too strongly or for too long, thereby moving the contents through the digestive tract too quickly. This causes the symptoms of abdominal pain, gas and bloating with alternating bouts of diarrhea and constipation. Although irritable bowel syndrome, which doctors at MayoClinic.com report affects one in five Americans, produces sometimes disabling symptoms, it does not cause inflammation or permanent damage to the bowel tissues.
