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Disorders associated with the upper digestive tract affect structures such as the esophagus, stomach, and the duodenum of the small intestine. Two relatively common upper digestive tract disorders are described here.
Gastroesophageal reflux disease (GERD), also commonly known as heartburn or acid reflux, is a disorder that affects the upper digestive tract. Acid reflux or “heartburn” occurs when the acidic digestive juices escape into the esophagus. This disorder occurs when chyme (which is very acidic) regurgitates into the esophagus because the lower esophageal sphincter does not properly close.
One complication from GERD is Barrett’s esophagus (BE). BE is a condition that occurs when the esophageal lining cells transform from squamous epithelium into specialized or intestinal-like columnar epithelium. Although BE is often benign, it is known to be a precursor for the development of esophageal adenocarcinoma, which is a type of cancer with a low survival rate.
As effective as the mucosal barrier of the digestive system is, it is not a “fail-safe” mechanism. Sometimes, gastric juice eats away at the superficial lining of the stomach or duodenal mucosa, creating erosions, which mostly heal on their own. Deeper and larger erosions are called ulcers. A peptic ulcer is an ulcer that occurs in either in the stomach or duodenum of the small intestine. A peptic ulcer that occurs in the stomach is also called a gastric ulcer, and a peptic ulcer that occurs in the duodenum is also called a duodenal ulcer.
Why does the mucosal barrier break down? A number of factors can interfere with its ability to protect the stomach lining. The majority of all ulcers are caused by either excessive intake of nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, or Helicobacter pylori infection. There is an increased risk of stomach cancer associated with H. pylori presence.
Antacids help relieve symptoms of ulcers such as “burning” pain and indigestion. When ulcers are caused by nonsteroidal anti-inflammatory drug (NSAID) use, switching to other classes of pain relievers allows healing. When caused by H. pylori infection, antibiotics are effective.
A potential complication of ulcers is perforation: Perforated ulcers create a hole in the stomach wall, resulting in peritonitis (inflammation of the peritoneum). These ulcers must be repaired surgically.
Any condition that causes damage to the liver and prevents it from properly functioning is called liver disease. Liver disease can be acute (occur over days or weeks) or chronic (occur gradually over months or years). In the United States, liver disease is the twelfth leading cause of death (American Liver Foundation, 2022). Chronic liver disease progresses in four stages: inflammation, fibrosis, cirrhosis, and end-stage liver disease (ESLD). Once ESLD occurs, the liver no longer can function or heal itself.
Hepatitis is inflammation of the liver. Inflammation of the liver caused by exposure to drugs, alcohol, toxins, or autoimmune disease is called nonviral hepatitis. Hepatitis can also be caused by viruses, which can be transmitted by body fluids such as blood or semen.
The most common types of viral hepatitis are A, B, C, D, and E. Fortunately, there are vaccines against hepatitis A and B. Causes, symptoms, and treatment options for hepatitis C, D, and E are described in the table below.
| Hepatitis (CDC, 2023) | |||
|---|---|---|---|
| Hepatitis Virus Type | Cause | Symptoms | Treatment |
| C | Exposure to blood or semen of an infected person; commonly transmitted through needle sharing from drug use or tattoos; can also be transmitted to an infant born to an infected mother |
Occur 2–12 weeks after exposure; can include
|
95% curable within 2–3 months with medications |
| D | Can only infect a patient who already has hepatitis B virus infection (called superinfection) or by being exposed to both simultaneously (called coinfection); transmitted through blood or body fluids |
Occur 3–7 weeks after infection; can include
|
There is no cure; treatment is based on supportive care |
| E | Fecal-oral route; transmitted by consuming contaminated or uncooked meats, such as pork, boar, venison, or seafood |
Occur approximately 40 days after exposure; include
|
Self-resolves without treatment |
In chronic liver disease, inflammation occurs as a natural response to injury, but liver cells are not able to properly regenerate. An overproduction of collagen is created from the persistent inflammatory state, stiffening the area and causing scarring or fibrosis to occur. Without treatment, the fibrosis continues, replacing healthy cells and leading to cirrhosis, or severe scarring of the liver. It is most commonly caused by chronic alcohol use and hepatitis. The cirrhosis continues until there are no healthy liver cells left, and the liver is no longer able to function, causing ESLD.
Acute liver disease progresses much more quickly and begins with inflammation, massive necrosis, and autonomous cellular dismantling of liver cells. The inflammation in the liver can trigger microglia activation in the brain, cause disruptions in the blood-brain barrier, and lead to astrocyte swelling and cerebral edema (Shah et al., 2023).
Treatment for liver disease includes treating the underlying cause with antivirals, corticosteroids, immunosuppressants, and substance use disorder treatment; healthy diet and lifestyle; and treating complications appropriately (Cleveland Clinic, 2023a).
There are a number of diseases that can severely impact the lower digestive tract, particularly the colon. If there is enough damage, a colectomy may be required to remove part of the colon. Some of the more common disorders of the lower digestive tract are described here.
Chronic inflammation of the GI tract is called inflammatory bowel disease (IBD). The two main types of IBD are Crohn’s disease and ulcerative colitis. Crohn’s disease (CD) is inflammation that can occur in multiple layers of the bowel, in any segment of the GI tract. The second main type, ulcerative colitis (UC), is inflammation that occurs only in the innermost wall of the large intestine and colon. IBD occurs in 1.3% of adults in the United States (CDC, 2022a) and most often in people aged 15 to 30 years old (McDowell et al., 2023).
Chronic mucosal inflammation in the GI tract occurs in IBD, leading to edema, bleeding, ulcers, and electrolyte loss. In UC, inflammation usually begins in the colon, then spreads, whereas CD can begin anywhere throughout the tract and can create a skip lesion, or a patchy area of inflammation that skips over some areas. CD can lead to complications, such as strictures and fistulas, and can predispose patients to other diseases, such as arthritis, kidney disease, and gallstones (McDowell et al., 2023).
Colorectal cancer is a cancer of the colon or rectum. This is a fairly common type of cancer, but fortunately, it can be detected by something called a colonoscopy. This is where a little camera is inserted into the colon to search for polyps, which are these growths that can be found on the colon wall and are a warning sign of possible colorectal cancer.
There is variable risk for colorectal cancer among demographics.
EXAMPLE
In the United States, this cancer is more prevalent in males than females. Additionally, the highest incidence for colorectal cancer has been observed in black individuals and the lowest incidence in Asian Americans and Pacific Islanders.The condition diverticulosis is the asymptomatic presence of diverticula, or sac-like protrusions, on the walls of the large intestine. Diverticulosis occurrence is 20% in adults aged 40 to 60 years, but up to 60% after the age of 60 (Pemberton & Strate, 2023). When diverticulosis becomes symptomatic, diverticular disease occurs; it is estimated to occur in 25% of people with diverticulosis (Tursi et al., 2020). A similar term, diverticulitis, refers to inflammation of the diverticula. The inflammation can remain contained or spread from the perforation to cause peritonitis, which you previously learned is inflammation of the peritoneum.
These last few disorders are malabsorption disorders. These disorders occur when certain vitamins or nutrients are not properly absorbed by the digestive system.
Cystic fibrosis (CF) is an inherited disease caused by a gene mutation that impacts how sodium and chloride ions travel across cell membranes. As a result, thick mucus accumulates in the lungs and throughout the body. Serious breathing problems occur, and it is strongly considered a respiratory disease. However, other physical issues can also occur with CF.
In CF, the pancreas does not provide enzymes for normal digestion and absorption of fats. Therefore, many patients with CF will experience digestion problems related to pancreatic insufficiency and require pancreatic enzyme supplementation as part of their treatment.
With diarrhea and constipation, water is not being properly absorbed. Either too much water is absorbed (constipation), or not enough water is absorbed (diarrhea), leading to one of these two conditions.
Diarrhea can occur when an irritant (such as bacteria, viruses, stress, infection) will cause the small intestine to secrete more water than the large intestine can absorb. This will result in diarrhea because the feces are mixed with an excess amount of water. This is something that can be frightening for children because if too much water is excreted from the body, it can lead to dehydration.
Diarrhea is a severe illness that can have devastating consequences. Worldwide, diarrhea is a leading cause of mortality for children under age five. Diarrhea can lead to dehydration, which has severe consequences if fluid and electrolytes are not replaced. Severe diarrhea causes a loss of chloride and bicarbonate ions, and death can occur from the resulting electrolyte imbalance.
Constipation is the opposite of diarrhea and occurs when feces remain in the rectum for too long, causing too much water absorption. Then, the feces become very hard and compressed, and difficult to pass.
An autoimmune disorder, celiac disease is triggered by gluten ingestion, which causes damage to the small intestine; gluten is a protein found in the wheat plant and other grains, such as barley and rye. Approximately 1% of the population is affected by celiac disease (Celiac Disease Foundation, n.d.). It is hereditary and can occur at any age and any time after gluten has been consumed.
In patients with celiac disease, the ingestion of gluten causes the body’s immune system to attack the villi (the small, finger-like cells that absorb nutrients) of the small intestine. This results in permanent damage over time, causing a scalloping of the folds and a cracked appearance of the mucosa, and disrupts the absorption of nutrients. The causes are unknown, and it is present when people with a genetic predisposition consume gluten.
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