The Digestive System and Body Metabolism

The digestive system is responsible for breaking down the food and drink we consume into usable substances and, transferring them into energy for our body; as well as for cell growth and repair. It consists of a network of organs working harmoniously to achieve the task. On top of harnessing the substances we consume, the digestive system is also responsible for excreting waste from the body. Metabolism is the process that your body uses to convert the food and drink that you consume into energy.  The digestive system and body metabolism work together to ensure that your body is consistently and efficiently energized to carry out normal day-to-day tasks, as well as background bodily functions.

Organs in Digestive System and Their Functions

Digestive Organ



This is where food enters the digestive system, and it contains many accessory organs that help with digestion.


The teeth are small, strong organs found within the mouth that are used to cut up large chunks of food into smaller pieces.


The tongue is a small organ found within the inferior portion of the mouth. It contains taste buds which are responsible for the sensation of taste. The tongue also helps to push food toward the back of the mouth, ready for swallowing.

Salivary Glands

Situated in the mouth, salivary glands release saliva when you are chewing. This moistens and lubricates the food, as well as begins the digestive process.


The pharynx allows the passage of food from the mouth into the esophagus. As the pharynx is also used for breathing, a small flap known as the epiglottis prevents food from entering the wind pipe.


The esophagus transports swallowed food to the stomach. At the end of the esophagus lies what is known as the cardiac sphincter, which closes to trap food within the stomach.


The stomach is found on the left side of the abdominal cavity and acts as storage for food, allowing the body to digest large meals effectively. The stomach also contains digestive enzymes and acids that continue the digestive process.

Small Intestine

The small intestine is a long thin tube that is responsible for the main extraction of nutrients from food that we eat. Once food has passed through the small intestine, it is estimated that 90% of the nutrients have been extracted.

Liver and Gallbladder

The livers main role in digestion is in the production of a substance known as bile, and the deliverance of bile to the small intestine. The gallbladder stores and recycles excess bile that was not required by the small intestine to break down foods.


The pancreas is a sizeable gland found within the stomach that produces and emits digestive enzymes into the small intestine.

Large Intestine

The large intestine’s main role in digestion is in the braking down of waste. The large intestine contains lots of symbiotic bacteria, which help to break down waste products and extract what nutrients are available. Feces within the large intestine are excreted from the body via the anal canal. 

Other Digestive Organs

Uvula, spleen, duodenum, transverse colon, descending colon, ascending colon, appendix, rectum, and anus.

How Human Body Metabolism Works

To understand the digestive system and body metabolism, knowing the organs involved and what roles they play is the first step, they we should learn how metabolism works. The process of metabolism can be split up in to two types, anabolism, and catabolism:

  • Anabolism – Also known as constructive metabolism supports the storage of energy for use at a later date, as well as cell growth and repair. During the process of anabolism, small molecules are transformed into larger molecules of fat, protein, and/or carbohydrates.
  • Catabolism – Also known as destructive metabolism, catabolism is the process of breaking down large fat, protein, and/or carbohydrate molecules to use for energy.

A gland called the pancreas secretes hormones to help your body to determine whether its main metabolic activity will be catabolic or anabolic.

The speed in which your body metabolized the food that you consume varies depending on the individual. An individual’s rate of metabolism is dependent upon the volume of thyroxine that is produced within the thyroid; thyroxine being a hormone that regulates metabolism.

Calories and Basal Metabolic Rate

The chemical process of metabolism is very complex, which has lead many people to look at it in the simplest way possible; it affects how easily you gain or loose weight. As we eat, we store calories (a calorie is a unit of measurement used to determine the quantity of energy given to the body by a particular food), the calories we store are later metabolized and utilized as energy. But, it is possible to overload on calories and end up with an excess amount, which is stored as body fat.

The amount of calories a person can burn in a day is dependent upon their basal metabolic rate (BMR), this is the measurement of the rate at which a person “burns” calories as energy. The higher a person’s BMR, the faster they can burn calories meaning less are stored as body fat. This means that they will be able to eat more and store less.

Although it is thought that a person’s BMR is inherited, there are steps you can take to increase yours. Exercise is the best method, as this will not only help you lose calories and stay fit, it is often the case that low body fat levels equals low BMR, and vice versa.

The video explains more about the digestive system and body metabolism:

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