How does the Digestive System Work?

How does the Digestive System Work?

French fries, diet soda, and pizza with extra cheese- the western diet and lifestyle are the perfect example of an “unhappy meal.” Combined with a sedative lifestyle and zero efforts to maintain health, it is slowly killing people.

Let’s be honest, Americans are eating way too much.  Almost one-third of the children and more than two-thirds of the adult population are obese. With every passing second, the number of digestive diseases is growing.

The health of your digestive system has so much to do with your lifestyle. It is determined by the amount of workout you do, the food you eat, and the level of stress you expose yourself to on a daily basis.

So what can you do to improve your digestive health and your lifestyle? The first and foremost thing to do is to develop an understanding of how your digestive system works.

Once you get a better hold on the intricate processes going on in your gut, you will know how to boost its health and save yourself from falling into the pit that you are constantly digging for yourself.

What is the Digestive System?

You have always been told how there is one and only one type of digestive system that exists in every living being- Wrong!

There are, in fact, four different types of digestive systems: avian, monogastric, pseudo-ruminant, and ruminant. The type that humans have is monogastric.

A monogastric digestive system is a rather simple system including a stomach with a single chamber. This is in opposition to other complex types in which there are multiple chambers in the stomach.

The digestive system is considered among one of the most important and major systems of the human body. It is a network of organs that function in synchrony to derive energy and nutrients from food and maintain a general wellbeing.

This incredible system includes some amazing combinations of hormones, nerves, blood, bacteria, and the digestive organs that work in harmony just to digest the pizza you have just eaten or the diet soda you have just sipped on.

But what is the main job of your digestive system? What is digestion, anyway?

Your digestive system is constantly in contact with other systems of the body. This includes immune systems, endocrine systems, and the nervous system.

Did you know that the process of digestion actually initiates in your brain?

The hypothalamus, an organ responsible for regulating various metabolic processes is what stimulates your appetite. It controls the health of your body organs and the state of your mind in response to stimuli, such as stress or ease.

Once it signals the gut, the process of digestion begins.

How long does it take for the food to digest in your body? The total time varies from person to person. On an average, it takes about 6 to 8 hours for the food to pass through the stomach, cross the small intestines and finally reach the large gut (colon). This transit time has been found to be relatively shorter for men than women, according to evidence.

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The Role of Digestive Organs

Before you can finally start paying attention to your digestive health, it is better to know about the organs that make up this system. The digestive system consists of numerous key parts. Let’s explore these parts one by one.


While a lot of people forget to include mouth as a part of your digestive system, it is actually an important site. Your mouth is where the breakdown of food practically begins.

Imagine taking off a bite off your favorite pizza: the first thing you do is chew it properly in your mouth unless it breaks down into pieces. The scrumptious taste of cheese and the sizzling jalapenos trigger the production of saliva which mixes with food to break it down further.

Once the food is properly broken down, you eventually swallow it, forcing it to enter esophagus: the next part of your digestive system.


Consider esophagus as a tube connecting your mouth with the stomach. It is like your mailman delivering mail (which, in this case, is the pizza you just ate) from the sender (mouth) to the recipient (the stomach).


The stomach is like a storage tank for your digestive system. It will receive the pizza and hold it for some time. This is to give your body enough time to digest the food properly.

But that’s not all. The stomach has a lot of other responsibilities. It not only stores food but also acts as a grinder and a mixer. The stomach secretes a lot of digestive enzymes and hydrochloric acid that accelerate the process of digestion.

So once the food makes its way to the stomach, it gets mixed with acids and enzymes. At this stage, the delicious-looking pizza that you just ate gets converted into a rather unpleasant material called chyme.

Chyme comes from a Greek word meaning juice. It is a semi-fluid mass formed in the stomach which is then further propelled into the intestines.

While the stomach prepares the food to be sent to the intestines, it is also secreting an acid called the hydrochloric acid. The purpose of this acid is not only to digest the protein but to destroy the harmful bacteria which may otherwise infect your digestive tract.

Hydrochloric acid is a colorless, clear, and extremely pungent solution of hydrogen chloride mixed in water. It is highly corrosive and acts as a digestive fluid and a bacteria-killer.

Once the stomach is done with its job, the chyme is moved into the small intestine.

Related– What are the signs of leaky gut syndrome?

Small Intestine

With a 20-feet length and one-inch diameter, the small intestine refers to a thin, long tube which further digests and assimilates food. But how does it function?

As soon as the stomach is done doing its part, it sends the chyme into the small intestine through a sphincter known as the pyloric sphincter. It is actually a muscle which allows food to pass into the small intestine and prevents its regurgitation back to the stomach.

The small intestine has a coiled structure. It consists of numerous ridges and folds where most of the absorptive processes occur. The small intestine has an alkaline environment in contrast to the stomach which is highly acidic due to the presence of hydrochloric acid.

Your small intestine has very tiny protrusions just to increase the total surface area. Why is this important, you ask?

A larger surface area ensures more absorption.

Within every protrusion, there are small structures called villi. These villi further have even smaller hair-like structures that you call microvilli. The villi are literally loaded with enzymes that break down whatever you have just eaten to convert into a more absorbable form.

The presence of these folds ensures maximum food digestion while guaranteeing that most of the nutrients are absorbed into the body. By the time the food (or whatever is left of it) leaves the small intestine, almost 90 percent of its nutrients have been absorbed into the blood. The leftover liquid goes through the small intestine into the large gut or colon.


Imagine a long, thick tube, around two and a half inches wide, running inside your body. Before you start getting creepy ideas about it, what you have just imagined in your colon.

Colon, or the large intestine, is the final resort for the digestive processes. While the juice coming from the small intestine is deprived of most of the nutrients, it still has some valuable amounts of fat-soluble vitamins, minerals, and water. The sole purpose of the colon is to extract all these.

Your colon naturally contains a lot of bacteria: the good ones, of course. These gut bacteria constitute the gut microbiome or flora. This bacterial flora acts on the remaining juice and extracts everything that possesses the slightest benefit for your health.

The waste material then exits your body through peristalsis: the contractions that move the waste towards the anal canal. In the beginning, the waste material is in a liquid form but as it moves through the colon, the water is reabsorbed, leaving behind solid to semi-solid excreta or the stools.

The stool mainly consists of bacteria and food debris. How long will it take for your colon to clean out? Almost 36 hours on average are required for the stools to pass through the colon. Once the colon becomes full, it empties into rectum which then initiates the process of excretion.

Accessory Organs

Did you think that was all? Think again.

While the main parts of your digestive system have been described above, there are a few accessory organs that are still left to be explained.


Spleen refers to an oval-shaped, flat lymphatic organ that filters your blood and protects your body from different infections. It is like a laundry house, constantly working to remove impurities from the blood, and destroying worn-out blood cells.

Additionally, the spleen is also your body’s blood bank. It stores blood to keep your body going in case of emergencies, such as injury.

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What is life and what does it do?

The liver is the second largest organ of your body and has a lot of hectic responsibilities. However, the main function of this organ is to produce bile and release it in the small intestine. It is also responsible for secreting bile which helps your body break down fats and release fatty acids.

The liver is an important site for detoxification. It cleanses and purifies your blood.

Once the nutrients from the food you eat get absorbed, they make their way to the blood. This blood then goes into the liver for getting filtered and detoxified.

Your liver has an incredible ability to break down amino acids and store them. It helps synthesize fats and cholesterol, remove toxins, store glucose, and makes sure that your body runs smoothly.


The gallbladder refers to a tiny organ that sits just under your liver. This pear-shaped organ is responsible for recycling and storing excess bile coming from the small intestine so that your gut can use it again in the future.

The bile acid produced by the liver is stored temporarily in the gallbladder. This traveling from the liver to the gallbladder is ensured by a pipe-like structure known as the cystic duct.

The gallbladder tends to store bile between the meals. As you start eating, it squeezes out some bile from the bile ducts i.e. the ducts that connect it to the small intestine.


Pancreas refers to a tube-shaped organ that secretes digestive enzymes into your small gut. With a spongy consistency, this six-inches long organ helps complete the chemical digestion of everything you eat.

The pancreas produces certain juices known as the pancreatic juices. These juices have a capacity to secrete carbohydrates, lipids, nucleic acid, and proteins.

One of the reasons why pancreas is extremely famous is its ability to secrete a hormone known as insulin. Insulin, in turn, helps regulate the blood sugar levels.

The hormones, as well as the enzymes produced by the pancreas, are required by your body to work properly.

Related– Emulsifiers and Colorectal Cancer – What’s the Link?

The Role of Spleen in Traditional Chinese Medicine

Western medicine recognizes spleen as an organ important for producing and destroying red blood cells. It is also involved in blood storage.

However, the Chinese concept of this organ is slightly different. The traditional Chinese beliefs include the role of the spleen in the assimilation of nutrients. It is also said to be involved in the maintenance of the physical endurance and stamina.

The spleen is used to convert digested food from the stomach into nutrients and qi: the life energy force.

In China, entire schools of medicine were formed around this organ because it’s believed that all aspects of life depend on the functioning of this essential organ, which allows the body to receive its needed nutrients.

In Eastern medicine, anemia and fatigue are considered to be the causes of splenic abruption. These conditions are said to arise as a result of the reduced ability of your spleen to gain energy from food.

So, if your spleen is weak, other parts of your body like the rectum, colon, stomach, or uterus may weaken.

As per the concepts of Eastern Medicine, a healthy diet and exercise can help the body only if your spleen is capable of transmitting energy and nutrients to your muscles. This means that a person with a malfunctioning spleen is bound to experience fatigue and weakness.

The spleen is not only recognized for its role in blood production and nutrition. It is also recognized as an organ important for transforming fluids. It helps in water metabolism, helps your body in getting rid of any excess fluid, and moistens the area which requires it.

The spleen is also important for separating the usable and the unusable fluids that you consume on a daily basis.

Signs of Digestive Issues

The digestive system diseases refer to the disorders of your digestive tract. They are also called the gastrointestinal tract diseases.

How do you figure out that your gastrointestinal system is acting up? Look out for the following symptoms:

  • Constipation
  • Diarrhea
  • Bleeding
  • Nausea
  • Vomiting
  • Weight fluctuations
  • Incontinence
  • Heartburn
  • Pain in the abdomen/belly
  • Swallowing problems
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Some of the digestive diseases that may produce the symptoms mentioned above include:

  • Gallbladder problems like Cholecystitis, gallstones, cholangitis
  • Rectal issues like hemorrhoids, fissures, rectal prolapse, and proctitis
  • Esophageal diseases like achalasia, stricture, esophagitis, and cancer
  • Stomach issues like gastritis, gastric ulcers, and cancer
  • Liver diseases like viral hepatitis, cirrhosis, fatty liver, and Wilson’s disease
  • Pancreatic involvement such as in pancreatic pseudocyst and pancreatitis
  • Intestinal issues like cancer, polyps, Crohn’s disease, irritable bowel syndrome, malabsorption, celiac disease, ulcerative colitis, and intestinal ischemia
  • Peptic ulcer disease, hiatal hernia, and gastroesophageal reflux disease

Foods to Maintain Digestion

Not sure how to improve your digestion? Start off by eating the right types of food. But what are the right types of food for a healthy digestive tract? Consider the following:

  • Raw cultured dairy
  • Bone Broth
  • Spices and herbs
  • Coconut products
  • Fermented vegetables and other items high in probiotics
  • Sprouted seeds such as flaxseeds, hemp seeds, and chia seeds
  • Foods rich in omega-3 fatty acids such as fatty fish
  • Miscellaneous nutrient-dense foods with anti-inflammatory properties like lamb, beef (grass-fed), fresh fruits and vegetables, sea vegetables, and vinegar

Final Thoughts

Your digestive system tends to play an important role in your overall wellbeing and health. The digestive system is divided into various parts, each with its own important functions and duties. All of this parts must be in optimal conditions and work harmoniously to bring out a good state of health.

Developing a good understanding of how your digestive system works together with healthy eating will ensure that your body works perfectly.

Nancy Walker

Nancy holds a Medicine degree and a Masters of Science MS in Infectious Disease and Global Health (MS-IDGH) from Tufts University. She worked as a lecturer for three years before she turned towards medical writing. Her area of interest are infectious diseases; causes, mechanism, diagnosis, treatments and prevention strategies. Most of her writings ensure an easy understanding of uncommon diseases.

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