How Gastrointestinal Tract Performs the Essential Role in Digestion?

The function of the gastrointestinal tract includes digestion, transportation, and absorption of food.

We consume food and drinks on a daily basis, but rarely take a moment to consider what exactly we put into our bodies, how our body reacts that what we are putting into it and how the digestive tract digests and processes the food we just consumed or the drink we just had. The gastrointestinal tract, which is home to the digestive system, is a complex part of the body that, essentially, is a long tube. It starts at the first organ that is connected to it, which is the mouth, and ends at the anus, where waste is expelled from the body.

How Gastrointestinal Tract Performs the Essential Role in Digestion?
The gastrointestinal tract is a part of the digestive system.

The digestive tract is always working and has many functions to perform to ensure food that we eat can be properly processed, digested, broken down and then to ensure any unused materials are pushed out of the body.

In this report, we will focus on the gastrointestinal tract, including what functions it serves, how exactly digestion works – from start to end, what makes the digestive tract work and also take a look at the different parts that make up the gastrointestinal tract.

At the end of this report, you will have a much better understanding of where food goes after you eat it, how the digestive system deals with what you eat, how the food you eat affects this particular system of your body and, finally, how waste is expelled from your body at the end of the digestive process.

Function and Purpose of the Gastrointestinal Tract

The primary function of the gastrointestinal tract, or the digestive system as you may also know it as, is to process the foods and liquids that we consume. This is quite obvious to the majority of people, yet most of those that knows the basic function of the digestive system are not aware of how exactly this particular system within their bodies really work. For this reason, we should start our article by considering the specific functions that the gastrointestinal tract plays in the human body, and how processes and digests food.

When we consume food, we place the food in our mouths, chew the food and then swallow. The moment we place the food in our mouths is when the digestive tract starts to work. This might sound somewhat unrealistic – but think about it. Chewing food is the digestive system’s way of preparing food for digestion. Through chewing, we essentially break food down into smaller pieces that will help the rest of the digestive system process the food. Saliva is also mixed with food as we chew it in the mouth, which contains certain enzymes that assists with the process of digestion.

Once chewed, we swallow food, which is then transported to the stomach. Here, food is broken down into particles that are small enough for absorption. The particles are known as nutrients. These nutrients play essential parts in maintaining our organs and the rest of our body, to ensure that everything functions correctly.

Nutrients Processed By the Gastrointestinal Tract

Nutrients Processed

The gastrointestinal tract takes food from your mouth through the esophagus, small and large intestines.

There are a large number of nutrients that the human body needs daily to survive and to function. When we do not provide our bodies with these essential nutrients, we may develop a condition known as malnutrition. Malnutrition occurs when the body does not gain an adequate supply of the most essential nutrients, and can lead to various symptoms that may even be life-threatening in some cases. There are different kinds of nutritional deficiencies that may occur, and each can develop a series of symptoms. Healthline reports that the most common nutritional deficiencies, as well as the symptoms they cause, include:

  • Iron Deficiency – This deficiency occur when the body lacks an adequate level of iron. A deficiency in iron can lead to a condition known as anemia, which is a lack of adequate blood in the body. This can cause symptoms such as weakness, fatigue and more.
  • Vitamin A Deficiency – When we do not consume an adequate supply of vitamin A, we may develop a compromised immune system as this particular vitamin helps to maintain a strong immune system that is able to ward off infection. A vitamin A deficiency may also cause blindness amongst children.
  • Thiamine DeficiencyThiamine is one of the eight B-vitamins, specifically vitamin B-1. This particular vitamin is essential for the conversion of carbohydrates into fuel, or energy, for the body, and plays vital parts in the metabolism process. A thiamine deficiency can lead to fatigue, cognitive impairment, such as memory loss, as well as weight loss.
  • Niacin Deficiency – Niacin is also part of the B-vitamin complex, specifically vitamin B-3. This particular nutrient is actually classified as a mineral and it also plays an important role in the metabolism process. Diarrhea, skin problems and dementia-related symptoms are common amongst individuals who have a niacin deficiency.
  • Folate Deficiency – More commonly known as folic acid or vitamin B-9, this vitamin is important for the production of DNA and red blood cells. It is also involved in the functioning of the nervous system and the brain. The most significant symptoms of folate deficiencies are seen as birth defects, which occurs when a pregnant woman has low folate levels in their body.
  • Vitamin D DeficiencyVitamin D is essential for bone health, as well as calcium regulation in the body. When a child has a vitamin D deficiency, they may experience stunted growth. A lack of this vitamin may also lead to symptoms related to osteoporosis.
  • Calcium Deficiency – Calcium is a common mineral that most people know about. It is promoted for healthy teeth and bones. In addition to its function on bones, calcium also assists with the function of muscles, nerves and the heart. When calcium deficiency is present, symptoms may not develop immediately, but rather cause more serious problems in the long run. Bone loss is the most common symptom of long-term calcium deficiency. Abnormal heart rhythms may also occur when a person has a low calcium level in their body.

Now that we understand how important nutrients are for the body, we should also consider the different types of nutrients that the body can process. During the process where the digestive system breaks food down into nutrient particles, the particular particles are split into four primary groups to prepare them for absorption into the bloodstream. Let’s discuss each of these particles individually to better understand the purposes they serve in the human body.


A protein is an important type of nutrient that is extracted from food sources that we consume. According to Genetics Home Reference[1], protein is a relatively large and complex type of molecule. It is involved in many functions of the human body.

Protein is also essential for cellular function and structure. Furthermore, all organs and tissue found within the body are reliant on protein for its function, regulation and its structure.Proteins can be broken down into smaller particles known as amino acids.

Amino acids attach to each other; thus forming long chains, which are what proteins are essentially. There are a total of 20 amino acids that can bind together, and the structure of each protein depends on the diversity and volume of amino acids attached to the chain. The structure of a protein defines its abilities and functions.

Some of the Most Important Proteins Include:

  • Enzyme – Enzymes are proteins that are responsible for chemical reactions that occur within cells present in the human body. Enzymes are also involved in the process of molecule production, and assist this particular process by extracting information from the genetics of a person’s DNA.
  • Structural Component – The sole function of structural components is to offer support, as well as information about structure, for cells in the body.
  • Antibody – An antibody protects the human body against bacteria and viruses. These proteins bind to particles in the body that seems foreign and unhelpful.
  • Messenger – These are essential proteins and mostly consist of hormones, such as the growth hormone. Messenger proteins are responsible for transmitting signals between organs, tissues and cells; thus allowing for adequate communication throughout the entire human body.
  • Transport And Storage – The purpose of these proteins are to bind small molecules to cells. Atoms can also be binded to cells through these proteins. After binding, these proteins help to transport these bindings through the human body.


Carbohydrates in Food

Carbohydrates provide energy to your body.

Carbohydrates are also important for the daily functioning of the body. These nutrients offer glucose to the human body, which can be used as an energy source after the carbohydrates have been processed by certain parts of the digestive system. In turn, the energy helps us perform physical activities and ensures bodily functions can work optimally.

It is very important to know that there exist both good and bad carbohydrates. While some carbohydrates will give you a proper dose of energy to last through the day and help keep you healthy, others will rather increase your risk of developing heart disease and diabetes.

According to Harvard T.H. Chan School of Public Health[2], carbohydrates can be divided into multiple groups, each with its own functions and purposes. The most common forms of carbohydrates include starches, fibers and sugars – all of which acts as fuel for the body’s energy system.


There are many different types of vitamins, and each play a particular role in maintaining various functions in the human body. Vitamins can either be fat soluble or water soluble. The soluble form of each vitamins is a vital feature to know as this tells you how the particular vitamin will act in the human body, and essentially also signals the best method for taking tablets that contain the particular vitamins.

According to Medicine Net[3], fat soluble vitamins are able to dissolve in fats, also known as lipids. After dissolving, chylomicrons, also called fat globules, will absorb the vitamins and then transfer it through the lymphatic system, and finally into the blood circulatory system.

A water soluble vitamin, on the other hand, does not require lipids to be observed into the body. It is important to understand that fat soluble vitamins are stored in the body, while excess water soluble vitamins are disposed of. This may have a potentially positive and negative effect – by storing the vitamins, fat soluble vitamins can work for longer, but when too much is stored, problems may develop.

There are a total of 13 essential vitamins that we need to include in our everyday meals and which the body can absorb and use for various functions. Medline Plus[4] reports that these essential vitamins include:

Vitamin A, Thiamine, Riboflavin, Niacin, Pantothenic Acid, Biotin, Folate, Vitamin C, Vitamin E, Vitamin K, Vitamin D, Vitamin B-6 & Vitamin B-12

Many of these vitamins play major parts in metabolism, brain function, the central nervous system and more; thus it is important to consume an adequate supply of these essential nutrients daily to avoid potential problems from arising.


When we hear the word fat, we tend to think about fat in the body – too much fat in the body causes obesity, which has negative implications on the human body. A lot of people also think of fat as a cholesterol-boosting food; thus end up avoiding foods that contain any kinds of fat.

Unfortunately, these statements often made by people are inaccurate, as the body requires a supply of healthy fats on a daily basis. There are good fats and there are bad fats. The bad fats are the ones that people often associated negative attributes with.[5] recommends avoiding to look for food that is low in fat, but rather to focus on buying food that contains high-quality fats. They continue to report that trans fats are the worst type of fat and also has the most significant adverse impact on human health.

Saturated fats are also bad for the body’s health and can cause the development of many health implications. Instead, a person should try to opt for unsaturated fats, which are considered good and healthy fats, to consume their daily fat requirements without experiencing the adverse impacts that the unhealthy fat choices may hold for the body.

Regulation of The Digestive Function

Regulation of The Digestive Function

Nerves and hormones regulate the digestive system.

When these nutrients are present in the gastrointestinal tract, after food particles have been broken down into smaller molecules, the digestive system can do its job more effectively. There are many processes involved with the digestive process, and each of these processes occur at a different region within the gastrointestinal tract.

According to the National Institute of Diabetes and Digestive and Kidney Diseases[6], the majority of the nutrients that were broken down from food sources are absorbed into the body while the molecules are present in the small intestine. These nutrients are then moved to appropriate body parts, where they can be stored for future use or to cause a chemical reaction, which may stimulate various functions.

The nutrients are absorbed into the blood circulatory system through the lining of the gastrointestinal tract in this particle area – special types of cells are responsible for this absorption process to be completed successfully.

Glycerol, amino acids, certain vitamins, salts and also simple types of sugar are all transported to the liver through the blood circulatory system, while a particle substance, medically known as lymph, carries other vitamins, as well as fatty acids, through the lymphatic system, where they can be absorbed and utilized for their particular functions.

The processes that occur within the digestive system can be controlled by one of two elements, which includes:

Nerve Regulators – Both intrinsic and extrinsic nerves are required by the digestive system. Intrinsic nerves are found inside the gastrointestinal tract, and are triggered when the stomach or the walls of another hollow organ is expanded due to food intake.

Several chemicals are released by these nerves to assist with the regulation of metabolism, such as to reduce the frequency of heartburn and to adjust digestive juices production.

Extrinsic nerves, also commonly known as outside nerves in the digestive tract, creates a connection between the organs that form part of the gastrointestinal tract, as well as the brain and the spinal cord.

Hormone Regulators – Within the stomach and the small intestine, hormone producing cells are found that can assist with regulating a person’s appetite.

These hormones also control the release of digestive juices, as well as play other parts in the many functions that the digestive tract needs to perform.

A Comprehensive Overview of The Gastrointestinal Tract

By now, you should have a better understanding of how the digestive system works, how it breaks food down and the particular nutrients it divides food in to help with absorption. The next step is to look at the gastrointestinal tract and discuss what this particular system in the body is made up of, as well as what functions each of the parts serves.

This will provide further knowledge to help you get a more comprehensive understanding of the gastrointestinal tract.

First of all, as we have already mentioned previously, the gastrointestinal tract is essentially a long tube in the human body. This tube starts at the mouth and ends at the anus. Digestion starts when we put food in our mouth, and it stops when the waste is released from the anus.

In reality, however, digestion never really stops, as we do not only eat once every third day, but rather multiples times each day. Thus, the gastrointestinal tract is constantly being regulated and stimulated to help food move downward, to extract vital nutrients from the food and then to expel the particles of food that was not used during digestion.

The tube that makes up the gastrointestinal tract is connected to several organs that make up a big part of the digestive system. Each part has its own function to play in the digestive process, and they all need to work together to ensure problems do not become present. Now, let us take a look at each of these organs individually, so that we can discuss their particular functions separately.

Hollow Organs In The Gastrointestinal Tract

Hollow Organs In The Gastrointestinal Tract

These hollow organs make up the gastrointestinal tract.

We will start by discussing the hollow organs that are part of the gastrointestinal tract. PubMed Health explains that the hollow organs are all relatively large, and they all contain a muscle layer against their walls.

This muscle layer has the ability to contract, which allows the organs to move food throughout the gastrointestinal tract. This process of food being moved through the digestive tract with the assistance of muscle layers attached to the walls of the hollow organs is called peristalsis.

The Mouth

The mouth is the starting point of the digestive system, as we have previously discussed in this report. The digestive process starts the second that we start to eat food or start to drink something. With the consumption of liquid, the digestive process does not start in the same way as with food in the mouth.

In such a case, the mouth acts like a transportation system to get the liquids to the stomach. When we eat food, however, the mouth is used to start breaking the food apart into smaller particles, and gets mixed with saliva, which is used to ease the digestive process.

InnerBody[7] reports that the salivary glands, the tongue and the teeth are also often referred to as organs that form part of the mouth. Once food has been chewed, the muscles in the mouth allow us to swallow the food we have chewed.

During this process, the soft palate found in the mouth will move over the nasopharynx that is present in the throat, which prevents food from going into a nasal cavity, which could lead to uncomfortable symptoms.

The pharynx, or as you may better know it as, the throat, is the next part of the body to receive the food after the mouth, which then moves the food downward to the esophagus.

The Esophagus

The next hollow organ in the human body, after the mouth, is the esophagus[8]. This organ is a tube that is made of muscular tissue. It connects the pharynx to the stomach, and is responsible for delivering food that comes from the mouth towards the next part of the gastrointestinal tract that will begin the official digesting process.

This hollow organ measures approximately eight inches in length in an adult person. The entire tube is lined with mucosa, a special pink tissue that has a moist texture. Prior to connecting to the stomach, the esophagus also runs through the body’s diaphragm.

It is important to also note that the esophagus contains a collection of muscles at its lower end, referred to the lower esophageal sphincter. These muscles are very important as they contract to avoid acids and other contents from the stomach from moving back into the esophagus towards the direction of the mouth.

The Stomach

Next up is the stomach. When food reaches the end of the esophageal, it gets pushed into the stomach. This is where the digestive process officially starts. When food is received by the stomach, special enzymes, as well as acids, are excreted into the stomach. These substances help with the digestion of the food that was consumed. A ridged lining is present in the stomach, which consists of special muscles called rugae. At intervals, the muscles of the stomach may contract, which helps with the digestion process.

Once food has been processed in the stomach, a small valve that is controlled by muscles, known as the pyloric sphincter, opens at the bottom part of the stomach. When the pyloric sphincter opens, food can travel into the small intestine from the stomach.

The Small Intestine

The majority of the functions that the digestive system performs to digest and process food occurs within the small intestine. This is also the first part of the intestines. This particular intestine is relatively thin, especially when compared to the large intestine, but it is much longer than the large intestine. LiveScience reports that the small intestine measures around 6.7 meters in length in the adult body.

In the small intestine, food particles are mixed with enzymes, bile, mucous and water; thus creating a watery substance that travels through the small intestine – this process, as previously discussed, is known as peristalsis.

The small intestine also consists of muscular tissue and can be divided into three different sections: the duodenum, which is responsible for breaking down food that was passed to the small intestine, is the first section of the small intestine.

After the part comes to the jejunum, as well as the ileum. Both of the last two sections are responsible for allowing the absorption of nutrients that were created from the breakdown process of the consumed food. These nutrients are delivered to the bloodstream in this process.

The Large Intestine

The large intestine is also called the colon. When food has been broken down and the nutrients have been absorbed by the body, the small intestine transports the remaining particles towards the large intestine, where the substance is still somewhat watery.

The large intestine has two primary functions[9] that play an essential part in the success of digestion. First, since the food that is contained in the beginning parts of the large intestine is watery, the purpose here is to absorb the excess water from the food that has been passed down to this particular part of the gastrointestinal tract.

Once water has been removed, all that remains is waste, or feces. Thus, the second primary function of the large intestine is to move the waste out of the body by elimination through the anus.

Read Next: Gastrointestinal Disease: Symptoms, Causes, Treatments, And Prevention

Solid Organs In The Gastrointestinal Tract

Solid Organs In The Gastrointestinal Tract

Liver, gallbladder, pancreas are the solid organ of the digestive system.

Solid organs are the particular organs that are not directly part of the gastrointestinal tract, but rather attached to this system. Food does not move through these organs. Instead, these organs play other parts in the digestive system, usually by secreting certain substances into the stomach to assist with the process of digesting and absorbing food molecules.

The Feeding Clinic of Los Angeles[10] reports that solid organs are also called accessory organs in many cases, since they are attached to the digestive tract like accessories, but this does not make their function and purpose in the digestive process any less significant.

The Liver

The liver is found on top of the stomach. It has a shape that is similar to a cone, with a dark brown/red color. The liver weighs approximately three pounds. The liver is quite complex, but our purpose here is to discuss how this particular solid organ is involved in the digestive system.

The liver is made up of two fundamental lobes, as reported by Hopkins Medicine[11]. Each of these lobes is divided into a total of eight segments, and then the segments are once again into around a thousand lobules.

These lobules are also called small lobes. The small lobes are connected to tubes that are called small ducts. One particular small duct, called the hepatic duct, delivers bile to the duodenum, which is part of the small intestine where substances are mixed with food to improve digestion of the molecules.

Note that the bile is produced by liver cells inside the liver. In addition to sending bile to the small intestine, the liver also delivers bile to the gallbladder.

The Pancreas

It is well-known that the pancreas[12] plays an important role when it comes to regulating levels of blood sugar, but this particular organ has other functions that are often misunderstood as well. The pancreas helps with the conversion of food into energy, which cells in the body can utilize for their functionality.

The two particular fundamental functions of the pancreas are called its exocrine and its endocrine functions. Exocrine function means it assists with digestion, while endocrine function means it assists with the regulation of blood sugar.

The Gallbladder

The gallbladder is something that is talked about a lot, yet most often misunderstood. It exhibits a pear-like shape and a hollow structure, but is still classified as a solid organ. The primary objective of the gallbladder is to store bile from the liver, and then to concentrate the bile; thus it provides a type of reserve or storage unit for bile that the liver sends to it.

According to Healthline[13], the body releases cholecystokinin when food is sent towards the small intestine from the stomach. Cholecystokinin is a type of hormone that tells the gallbladder to release some bile acid into the small intestine.


The gastrointestinal tract is one of the most important systems in the human body. This system has many vital features to perform, with the most significant being the digestive process, where food is broken down into nutrients, transferred through the digestive tract and sent into the blood circulatory system to provide essential nutrients to all vital parts of the body.

In addition to this function, the gastrointestinal tract also contains the body’s first defensive mechanism against potentially harmful substances, such as bacteria that cause disease or infection.

In this report, we provided detailed information about the function of the digestive system, as well as discussed the numerous hollow and solid organs that make up the gastrointestinal tract; ultimately offering the reader in-depth information about how their digestive tract works and what happens to the food and liquids they consume.

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