The Digestive System & How it Works

What is the Digestive System?

The digestive system is made up of the gastrointestinal (GI) tract—also called the digestive tract—and the liver, pancreas, and gallbladder. The GI tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. The hollow organs that make up the GI tract are the mouth, esophagus, stomach, small intestine, large intestine—which includes the rectum—and anus. Food enters the mouth and passes to the anus through the hollow organs of the GI tract. The liver, pancreas, and gallbladder are the solid organs of the digestive system. The digestive system helps the body digest food.

Bacteria in the GI tract, also called gut flora or microbiome, help with digestion. Parts of the nervous and circulatory systems also play roles in the digestive process. Together, a combination of nerves, hormones, bacteria, blood, and the organs of the digestive system completes the complex task of digesting the foods and liquids a person consumes each day.

Why is Digestion Important?

Digestion is important for breaking down food into nutrients, which the body uses for energy, growth, and cell repair. Food and drink must be changed into smaller molecules of nutrients before the blood absorbs them and carries them to cells throughout the body. The body breaks down nutrients from food and drink into carbohydrates, protein, fats, and vitamins.

Carbohydrates. Carbohydrates are the sugars, starches, and fiber found in many foods. Carbohydrates are called simple or complex, depending on their chemical structure. Simple carbohydrates include sugars found naturally in foods such as fruits, vegetables, milk, and milk products, as well as sugars added during food processing. Complex carbohydrates are starches and fiber found in whole-grain breads and cereals, starchy vegetables, and legumes. The Dietary Guidelines for Americans, 2010, recommends that 45 to 65 percent of total daily calories come from carbohydrates.1

Protein. Foods such as meat, eggs, and beans consist of large molecules of protein that the body digests into smaller molecules called amino acids. The body absorbs amino acids through the small intestine into the blood, which then carries them throughout the body. The Dietary Guidelines for Americans, 2010, recommends that 10 to 35 percent of total daily calories come from protein.1

Fats. Fat molecules are a rich source of energy for the body and help the body absorb vitamins. Oils, such as corn, canola, olive, safflower, soybean, and sunflower, are examples of healthy fats. Butter, shortening, and snack foods are examples of less healthy fats. During digestion, the body breaks down fat molecules into fatty acids and glycerol. The Dietary Guidelines for Americans, 2010, recommends that 20 to 35 percent of total daily calories come from fat.1

Vitamins. Scientists classify vitamins by the fluid in which they dissolve. Water-soluble vitamins include all the B vitamins and vitamin C. Fat-soluble vitamins include vitamins A, D, E, and K. Each vitamin has a different role in the body’s growth and health. The body stores fat-soluble vitamins in the liver and fatty tissues, whereas the body does not easily store water-soluble vitamins and flushes out the extra in the urine. 

How Does Digestion Work?

Digestion works by moving food through the GI tract. Digestion begins in the mouth with chewing and ends in the small intestine. As food passes through the GI tract, it mixes with digestive juices, causing large molecules of food to break down into smaller molecules. The body then absorbs these smaller molecules through the walls of the small intestine into the bloodstream, which delivers them to the rest of the body. Waste products of digestion pass through the large intestine and out of the body as a solid matter called stool.

Table 1 shows the parts of the digestive process performed by each digestive organ, including movement of food, type of digestive juice used, and food particles broken down by that organ.

Table 1. The Digestive Process

How Does Food Move Through the GI Tract?

The large, hollow organs of the GI tract contain a layer of muscle that enables their walls to move. The movement of organ walls—called peristalsis—propels food and liquid through the GI tract and mixes the contents within each organ. Peristalsis looks like an ocean wave traveling through the muscle as it contracts and relaxes.

• Esophagus. When a person swallows, food pushes into the esophagus, the muscular tube that carries food and liquids from the mouth to the stomach. Once swallowing begins, it becomes involuntary and proceeds under the control of the esophagus and brain. The lower esophageal sphincter, a ringlike muscle at the junction of the esophagus and stomach, controls the passage of food and liquid between the esophagus and stomach. As food approaches the closed sphincter, the muscle relaxes and lets food pass through to the stomach.
• Stomach. The stomach stores swallowed food and liquid, mixes the food and liquid with digestive juice it produces, and slowly empties its contents, called chyme, into the small intestine. The muscle of the upper part of the stomach relaxes to accept large volumes of swallowed material from the esophagus. The muscle of the lower part of the stomach mixes the food and liquid with digestive juice.
• Small intestine. The muscles of the small intestine mix food with digestive juices from the pancreas, liver, and intestine and push the mixture forward to help with further digestion. The walls of the small intestine absorb the digested nutrients into the bloodstream. The blood delivers the nutrients to the rest of the body.
• Large intestine. The waste products of the digestive process include undigested parts of food and older cells from the GI tract lining. Muscles push these waste products into the large intestine. The large intestine absorbs water and any remaining nutrients and changes the waste from liquid into stool. The rectum stores stool until it pushes stool out of the body during a bowel movement.

How Do Digestive Juices in Each Organ of the GI Tract Break Down Food?



Digestive juices contain enzymes—substances that speed up chemical reactions in the body—that break food down into different nutrients.

• Salivary glands. Saliva produced by the salivary glands moistens food so it moves more easily through the esophagus into the stomach. Saliva also contains an enzyme that begins to break down the starches from food.
• Glands in the stomach lining. The glands in the stomach lining produce stomach acid and an enzyme that digests protein.
• Pancreas. The pancreas produces a juice containing several enzymes that break down carbohydrates, fats, and proteins in food. The pancreas delivers digestive juice to the small intestine through small tubes called ducts.
• Liver. The liver produces a digestive juice called bile. The gallbladder stores bile between meals. When a person eats, the gallbladder squeezes bile through the bile ducts, which connect the gallbladder and liver to the small intestine. The bile mixes with the fat in food. The bile acids dissolve fat into the watery contents of the intestine, much like how detergents dissolve grease from a frying pan, so the intestinal and pancreatic enzymes can digest the fat molecules.
• Small intestine. Digestive juice produced by the small intestine combines with pancreatic juice and bile to complete digestion. The body completes the breakdown of proteins, and the final breakdown of starches produces glucose molecules that absorb into the blood. Bacteria in the small intestine produce some of the enzymes needed to digest carbohydrates.

The Medical Perspective

Life-threatening Causes of Digestive Swelling

In some cases, digestive symptoms may accompany a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

• Abdominal abscess
• Abdominal trauma
• Acute pyelonephritis (kidney infection)
• Bleeding esophageal varices
• Bleeding peptic ulcer
• Bowel obstruction
• Brain hemorrhage
• Diabetic ketoacidosis (serious complication of diabetes)
• Dissecting abdominal aortic aneurysm
• Kidney failure
• Liver failure
• Peritonitis (infection of the lining that surrounds the abdomen)



What are the Potential Complications of Digestive Symptoms?

In some cases, digestive symptoms can lead to serious complications, especially if the underlying disease or condition is untreated or poorly managed. Once the underlying cause is identified, you can help minimize your risk of serious complications by following the treatment plan you and your health care professional design specifically for you. Complications include:

• Bowel obstruction
• Dehydration due to vomiting, diarrhea, or a decreased desire to drink fluids
• Difficulty breathing
• Erosive esophagitis
• Peritonitis
• Poor nutrition due to vomiting, diarrhea, or a decreased desire to eat
• Reduced appetite
• Sepsis (life-threatening bacterial blood infection)
• Severe discomfort or pain
• Shock

Treatments and Solutions

The Alternative Perspective

Dr. Huntoon has helped hundreds of people from all over the country to deal with this challenging disorder. Focusing on the underlying CAUSE has always resulted in full resolution of the imbalance. Taking the time to have a Consultation and Examination with Dr. Huntoon will always prove beneficial. Regardless of what you call it, you can restore your health and return to a normal life. 

By working closely with a Holistic Chiropractor who can help you develop a well-rounded, multifaceted approach to addressing your digestive concerns and cravings is warranted. Make sure to address any negative effects caused by antibiotic therapy by getting on a proper probiotic. Your Holistic Chiropractor can advise you of this.

Digestive symptoms can result from gastrointestinal or digestive conditions or from conditions of other body systems, such as the endocrine system, the nervous system, the reproductive system, and the urinary system. Many times emotions will create digestive symptoms and by working with a Holistic Chiropractor who practices Neuro-Emotional Technique (NET) is warranted. For more information on NET, go to www.netmindbody.com

Also consider working with an Acupuncturist, Homeopath or Naturopath to develop a lifestyle that can support and manage your digestive problems.

Medicines Two Choices for You 

Your Solution



Developing a healthy life-style with proper guidance from your Holistic Chiropractor is the best prevention. Asking questions about what you can do to develop a Preventative mindset is important.

Dr. Huntoon has helped hundreds of people from all over the country to deal with this challenging disorder. Focusing on the underlying CAUSE has always resulted in full resolution of the imbalance. Regardless of what you call it, you can restore your health and return to a normal life. 

Do not listen to the television commercials that will say, "There is no cure for your condition. Management can be achieved. Ask your doctor today if this medication is right for you." 

If you are ready to get to the source of your problem, we are here to help. Call Dr. Huntoon at (845)561-2225 and schedule your consultation today. We look forward to serving you.