Gastroenterology is the branch of medicine that focuses on disorders of the esophagus, stomach, intestines, pancreas, gallbladder and other organs that comprise the digestive system. It is one of the oldest branches of medicine, since food processing and the excretion of bodily wastes are processes that are absolutely essential to health.
Disorders of the Esophagus
The esophagus is the tube through which food travels from the mouth to the stomach. The upper third of the esophagus is ringed with striated muscle to facilitate conscious swallowing.
Gastroesophageal reflux disease (GERDs) is the most common disorder of the esophagus. The gastroesophageal juncture between the stomach and the esophagus is not a perfect valve, and acidic stomach contents can leak back into the esophagus causing pain, nausea and vomiting. Depending upon the extent of the reflux, patients can also experience sore throat, laryngitis and bad breath.
Disorders of the Stomach
Starch digestion begins in the mouth, but the stomach is the part of the digestive system where most food processing begins. Parietal cells in the stomach lining produce hydrochloric acid. This acid activates other glands to begin secreting pepsin, an enzyme essential to protein digestion.
The lining of the stomach is very tough to prevent it from being digested by the dual action of hydrochloric acids and enzymes. Under certain circumstances, however, this corrosive combination will damage the stomach walls. The damage may be catalyzed by the long-term use of non-steroidal anti-inflammatory drugs such as ibuprofen or aspirin, or by a Helicobacter pylori bacterial infection.
Peptic ulcers are sores in the lining of the stomach. They are characterized by a sensation of burning pain. The pain goes through periods of exacerbation and remission, and is most severe when the stomach is empty.
Disorders of the Intestines
The intestines consist of two parts: the small intestine and the large intestine. Digestion begins when bile and pancreatic juices are secreted into the duodenum, the initial segment of the small intestine. Most of the nutrients the body needs are separated from the food bolus in the small intestine.
The large intestine is shorter but wider than the small intestine. It's the body's waste filtration system, separating water, sodium, chlorine and other electrolytes from the food bolus. The large intestine is populated with beneficial bacteria that help in this phase of the digestive process.
Peptic ulcers can occur in the duodenum. Other disorders of the small intestine include:
• Celiac disease: An allergy to gluten that causes diarrhea and abdominal pain.
• Crohn's disease: An autoimmune disease that can cause severe abdominal pain, severe diarrhea, intestinal blockage and malnutrition.
• Irritable bowel syndrome: An idiopathic condition that causes abdominal cramping, abdominal bloating and changes in bowel regimens.
• Various types of cancer.
Disorders of the large intestine include:
• Irritable bowel syndrome
• Ulcerative colitis: An autoimmune disease that causes severe abdominal pain and bloody diarrhea.
• Diverticulitis: Unusual pouches in the walls of the large intestine that may or may not be symptomatic.
Disorders of the Pancreas
The pancreas is an abdominal gland, located behind the stomach, next to the duodenum. It functions both as an exocrine and endocrine gland, producing digestive hormones that help with the digestion of food in the duodenum, as well as the insulin that regulates blood glucose levels.
Pancreatitis is an inflammation of the pancreas caused by digestive enzymes. Pancreatitis symptoms include severe pain in the upper abdomen, nausea and vomiting. Acute pancreatitis is often caused by gallstones. Chronic pancreatitis can be caused by chronic alcoholism, autoimmune diseases and high serum calcium levels.
Disorders of the Gallbladder
The gallbladder is a pear-shaped organ located near the liver that acts as a storage place for the bile, a surfactant produced by the liver that aids in lipid digestion.
The gallbladder connects to the liver by means of a duct. Occasionally, that duct will become blocked. The culprit is generally a gallstone, a hardened piece of bile and cholesterol. The symptoms of a gallstone attack include nausea, vomiting and abdominal pain, particularly when experienced right after a meal.