Digestive System Anatomy for Hepatitis Patients

Introduction to Digestive System Anatomy

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The digestive system is composed of organs that work together in order to convert food, which is being supplied as basic nutrients needed by the body, into energy. Essentially, the digestive system is a long tube that’s open from two ends. Food enters at one end, then passes through a long tube inside the body called gastrointestinal tract where the nutrients the body can use are absorbed, and the residue that is not digested is excreted from the other end.

The system of digestion goes as simple as that. The digestive system, of which the liver is often considered a part, involves important and complicated processes essential in the body’s absorption of nutrients. This process starts from the ingestion of food.

Essentially, the key functions of the GI tract are to ingest and transport the food, secrete the fluids and enzymes needed for the digestion, absorb the digested products, and eliminate the indigestible waste remains. Notwithstanding, to further understand how each organ involved in the GI tract work together, and how other organs from different systems of the body compel to each other, it is imperative for hepatitis patients to understand first where the tract starts – the mouth.

Anatomy and Hepatitis: Gastrointestinal Tract

The gastrointestinal tract is basically the long tube pathway through the body where the food pass as it gets through the digestive system.

It functions as a gateway for the food as it enters the mouth, and a pathway as it careens through the pharynx and ​esophagus. The GI Tract also serves as a sac reservoir as the chewed food is digested in the stomach, before it is absorbed by the body as the nutrients are being taken to the other anatomical structures to be broken down further and distributed.

Lastly, it acts as a “waste expeller” as the non-digested materials are excreted at the bottom of the tube through anus.

All these functions are not completed through the GI tract alone. The enzymes, salivary glands, pancreas, liver, gall bladder, and other organs and fluids help digest food and transport the nutrients. Each organ is being triggered by hormones which tell the whole body system to function accordingly. Hence, the digestive system is connected and related to the other systems of the body. It is connected to the circulatory system as the organs in it, such as the liver, are the ones responsible in transporting and/or processing the nutrients from the intestine to the tissues throughout the whole body. The nervous system, which often affects hepatitis patients profoundly when there is a disorder, also helps in controlling the enzymes to be released, as well as the muscular contraction of the digestive system. These muscles provide motility in order to digest and move the food through the GI tract. The hormones and the enteric nervous system’s extrinsic autonomic nerves police the activity of the GI tract.

Where Things Get Rolling: Upper GI Tract

The first open end of the digestive system where the food begins its excursion is the mouth.

The teeth inside the mouth are charged with chewing and tearing food apart into smaller bits. The saliva, which is a mucous substance, is being secreted and lubricates everything to kick off the dissolving process. Saliva is composed of enzymes which start the process of digestion of carbohydrates and fats which are to be brought farther down the digestive tract. Hepatitis patients should understand that it serves as an “adhesive,” as it holds the food together en route for the stomach. The chewed food fastened with saliva is turned into a ball-piece called a bolus – which is transported towards the esophagus.

There are involuntary muscles in the esophagus that wither and induce the food into the stomach.

As the food has been chewed in with the salivary glands turning it into bolus and is then swallowed, it will move from mouth to the pharynx. The pharynx, or mostly called throat, acts a filtering ingress to the esophagus. Hepatitis patients should also note that aside from food passage to the esophagus, pharynx also carries air to the windpipe and larynx. Leading from the pharynx to the stomach, the esophagus is a hollow conduit that has muscular walls which propel the food through rhythmic waves of muscles that contract involuntarily. This process is known as peristalsis. In the event of peristaltic contraction when the bolus has been swallowed, smooth muscles behind the bolus are contracting so that it would not cram back to the mouth. There is a rhythmic wave that will rapidly force the bolus to be push toward the stomach. The process of peristalsis is a one-direction movement only, to propel and keep the food moving downwards to the stomach.


Kararli TT. Comparison of the gastrointestinal anatomy, physiology, and biochemistry of humans and commonly used laboratory animals. Biopharm Drug Dispos. 1995 Jul;16(5):351-80.

Ménard D. Functional development of the human gastrointestinal tract: hormone- and growth factor-mediated regulatory mechanisms. Can J Gastroenterol. 2004 Jan;18(1):39-44.

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