The Digestive System

From Mouth to Large Intestine, Your Digestive System Is a Wonder

The digestive system includes many different organs with a wide variety of different functions. Digestion begins with the mouth, but also includes a breakdown of food into nutrients that can be absorbed for our bodies' use. Waste products must be properly processed and excreted. If the process breaks down at any point, we run into serious problems.

While the process of eating can take just a few moments, digestion takes quite a while -- hours, or even days.

From Mouth to Stomach

Mouth:  Even before you start to eat, you may smell the delicious odor of food cooking. This starts your mouth watering in preparation for digestion. Once you take a bite, chewing breaks food down into smaller particles so it can be digested. If people do not chew food thoroughly because they eat quickly or have tooth problems, they increase the burden on the digestive organs. Saliva contains the digestive enzyme amylase, which begins breaking down starchy foods as soon as they enter the mouth.

Esophagus: The esophagus is a tube that runs from the back of the throat to the stomach. Its entire purpose is to push chewed food into your stomach. Muscles in the esophagus move in a wave-like motion to ensure food makes its way down. The trachea, used for breathing, is another tube located very close to the esophagus; when food goes into the trachea by mistake, it is coughed up.

Stomach:  The stomach stores food while it releases acids that chemically break down food. Hydrochloric acid, often called stomach acid, plays a key role in the stomach. It helps digest proteins, fat, vitamins, and minerals, maintains the acidity of the stomach, and helps kill bacteria, viruses, and parasites.

Mucus coating the stomach's walls protects your body from acid burns.

The Small and Large Intestines

Once your food has been processed in your stomach, it makes its way into the small and large intestines. These important organs supported by the pancreas, gall bladder, liver, and kidneys, complete the digestion and excretion process.

Small Intestine:  The small intestine is only about 2-3 inches wide, but stretched out it is about 22 feet long. Enzymes from the pancreas and small intestine are released into the small intestine to digest and absorb carbohydrates, fat, and protein. In addition, bile salts secreted from the gallbladder help with the digestion and absorption of fats and the fat soluble nutrients vitamin A, D, E, and K.

The small intestine is the primary organ involved in the absorption of nutrients. Anything that interferes with the secretion of enzymes or bile salts, or disrupts the absorptive walls of the small intestine, such as inflammatory bowel syndrome, chronic antacid use, chronic diarrhea, pancreatic insufficiency, or celiac disease, may result in vitamin deficiencies and fat malabsorption.

Nutrient rich blood is processed by the liver. The liver's function is to filter out any waste or harmful materials.

Large Intestine:  The large intestine is also known as the colon. By the time food reaches the colon, most of the nutrients have already been absorbed, leaving indigestible fiber and water. The large intestine absorbs water, electrolytes, and a few vitamins. The length of time taken for food to pass through the colon largely depends on fiber intake. Mucus is secreted to protect the cells lining the colon from physical trauma and bacterial toxins.


The large intestine processes waste so that it can be excreted as feces (poop). Liquid waste is excreted as urine. Just as problems with the large and small intestine can cause serious illness, so, too, problems with the anus, bladder, and other organs related to excretion can lead to illness.

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