The digestive system is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. Inside this tube is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food. There are also two solid digestive organs, the liver and the pancreas, which produce juices that reach the intestine through small tubes. In addition, parts of other organ systems (for instance, nerves and blood) play a major role in the digestive system.
When we eat such things as bread, meat, and vegetables, they are not in a form that the body can use as nourishment. Our food and drink must be changed into smaller molecules of nutrients before they can be absorbed into the blood and carried to cells throughout the body. Digestion is the process by which food and drink are broken down into their smallest parts so that the body can use them to build and nourish cells and to provide energy.
Digestive diseases are disorders of the digestive tract, which is sometimes called the gastrointestinal (GI) tract.
In digestion, food and drink are broken down to small parts (called nutrients) that the body can absorb and use as energy and building blocks for cells.
The digestive tract is made up of the esophagus (swallowing tube), stomach, large and small intestines, liver, pancreas, and the gallbladder.
The first sign of problems in the digestive tract often includes one or more of the following symptoms:
Bleeding
Bloating
Constipation
Diarrhea
Heartburn
Incontinence
Nausea and vomiting
Pain in the belly
Swallowing problems
Weight gain or loss
A digestive disease is any health problem that occurs in the digestive tract. Conditions may range from mild to serious. Some common problems include cancer, irritable bowel syndrome, and lactose intolerance.
Other digestive diseases include:
Gallstones, cholecystitis, and cholangitis
Rectal problems, such as anal fissure, hemorrhoids, proctitis, and rectal prolapse
Esophagus problems, such as stricture (or narrowing) and achalasia
Liver problems, such as hepatitis B or hepatitis C, cirrhosis, liver failure, and autoimmune and alcoholic hepatitis
Pancreatitis and pancreatic pseudocyst
Intestinal problems, such as infections, celiac disease, Crohn's disease, ulcerative colitis, diverticulitis, malabsorption, short bowel syndrome, and intestinal ischemia
Gastroesophageal reflux disease (GERD), peptic ulcer disease, and hiatal hernia
Diagnostic tests for digestive problems can include colonoscopy, upper GI endoscopy, capsule endoscopy, endoscopic retrograde cholangiopancreatography (ERCP), and endoscopic ultrasound.
Many surgical procedures are performed on the digestive tract. These include procedures done using endoscopy, laparoscopy, and open surgery. Organ transplants can be performed on the liver, pancreas, and small intestine.
Many health care providers can help diagnose and treat a patient’s digestive problems. A gastroenterologist is a physician specialist who has received extra training in the diagnosis and treatment of the digestive disorders. Other health care providers involved in the treatment of digestive diseases include:
Nurse practitioners (NPs) or physician assistants (PAs)
Nutritionists or dietitians
Primary care doctors
Radiologists
Surgeons
The human digestive system is a sequence of organs that use mechanical and chemical means to take in food, break it down, extract nutrients and energy, and eject waste products in the form of urine and feces.
The mouth is the entrance to the human digestive system. Teeth gnash the food, breaking it down mechanically, while the three salivary glands release saliva containing the enzyme amylase, which breaks down starch and fat chemically. Saliva makes food easier to swallow by moistening it, as well as preventing the erosion of tooth enamel by modulating pH.
After entering the body at the back of the throat, food travels down the esophagus, being transported not by gravity but by muscular contractions. This is why it is possible to eat while hanging upside down. The interior of the esophagus is very moist, which helps to further break down food and prevent damage to the rest of the digestive system.
After moving through the esophagus portion of the digestive system, food and drink reaches the stomach, where it is further broken down into manageable pieces. Because the nutrients in food are ultimately meant to be consumed by cells, they must be broken into very small parcels for delivery. The primary agent of digestion in the stomach is gastric juices, which are produced in large amounts and can be very acidic. A secondary agent is muscular contractions within the stomach.
After the stomach, the broken down food moves into the small intestine, the portion of the digestive system where most of the nutrient extraction takes place. As the food moves through the small intestine, it is mixed with bile, which is produced by the liver, as well as pancreatic juices, which come from the pancreas. These two liquids help further the digestive process, breaking down the nutrients in food to the point where it can be absorbed by the blood. The inner intestine is home to the famous villi, tiny living extrusions which gather nutrients on a fine scale.
The final components of the digestive system are the large intestine or colon, the anus, and the urinary tract, which separate the liquid matter from the solid matter and send them to their respective exit ports.