“Gastrointestinal diseases are health conditions that affect your gastrointestinal (GI) tract. Your GI tract is the path food takes through your digestive system — from your mouth to your rectum. It also includes your liver, pancreas and gallbladder. Some digestive system diseases cause problems that go away relatively fast with treatment. Others cause problems that are more serious.

GI diseases can be acute or chronic:

• An acute GI disease is one that happens suddenly and lasts a short period of time.
• A chronic GI disease can affect you for many months or years.

They can also be either functional or structural:

• A functional GI disease is when your healthcare provider can’t see any physical or structural issues when they examine your digestive tract.
• A structural GI disease is when your healthcare provider can see evidence of an issue when they examine you.

Functional gastrointestinal diseases

You’ve likely experienced several functional GI problems in your lifetime. Constipation, gas and diarrhea are examples of functional GI diseases. These types of GI diseases irritate your GI tract and lead to uncomfortable symptoms.

Some of the most common causes of functional GI problems are:

• Eating a diet low in fiber or high in processed foods
• Not getting enough exercise
• Traveling or other changes in your typical routine
• Stress and anxiety
• Holding your poop or not going as soon as you need to go
• Taking certain medicines
• Hormonal changes (like pregnancy or during menstruation)
• Food sensitivities or eating something that didn’t “agree” with you

Treatment for functional GI diseases usually involves lifestyle changes like eating more fiber-rich foods, getting more physical activity or avoiding triggers. Sometimes, functional problems go away on their own within a few days.

Structural gastrointestinal diseases

Structural GI diseases are typically more complicated. They tend to cause symptoms that last longer and don’t get better with lifestyle changes alone. Structural problems cause issues your provider can see such as inflammation or blockages. Common examples of structural GI diseases include hemorrhoids, colon polyps and inflammatory bowel disease (IBD). Causes of structural GI diseases are more widespread.”

Cleveland Clinic (Gastrointestinal Diseases: Symptoms, Treatment & Causes)