Digestive system: anatomy, parts and function

Contrary to what many people believe, the digestive process does not just involve mixing food with gastric acids in the stomach.

Both chemical and physical actions are carried out, beginning in the mouth with ingestion and ending at the end of the digestive tract with egestion.

In this article we will talk about the digestive system, what bodies make it up and what functions each of them perform.

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The digestive system

In essence, this system is made up of all the organs that are involved in the process of digestion, which consists of transform food into nutrients that can be used by the body so that it can maintain its functions physiological.

Its main function is to extract the nutrients that are present in the food through the action of enzymes and physical processes that transform food into smaller elements. Once this has been done, the nutrients are absorbed and incorporated into the bloodstream, through which they will travel throughout the body to reach the cells. Metabolic reactions take place inside cells that give energy and substances to maintain cell structure.

In addition to nourishing at the cellular level, the digestive system is responsible for getting rid of those substances that are not beneficial for the body, whether they are non-useful or toxic substances and pathogens. These elements are what will make up the feces, which will be eliminated through egestion.

Below we explain all the parts that make up this system, in addition to presenting them in the order in which digestion occurs and what their fundamental functions are during this process.

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Digestion: the path of food through us

This is the path that food takes to pass through the nervous system.

1. Mouth

The mouth is the gateway for food to our body and the place where the first phase of digestion occurs: ingestion.

Here food is reduced by chewing, breaking it down through physical action and transforming it into smaller parts.

In addition to this, saliva, a liquid that contains enzymes that break down starches in food, is secreted into the mouth. This is the first chemical reaction that food undergoes once it has been incorporated into the body.

The tongue is responsible for pushing food down the throat. Before reaching the esophagus, it is necessary to prevent food from going down the wrong path and being introduced into the lungs. For this reason, the epiglottis, a structure found in the trachea, folds, closing the entrance to the respiratory system and preventing choking.

2. Esophagus

Once food has been swallowed, it travels through the esophagus. It is a tube through which food is carried to the stomach. For this, the action of muscles is necessary, which perform movements called peristaltic.

3. Lower esophageal sphincter

It is the part that separates the esophagus from the stomach, being the gateway to this second. So that food can be introduced into the stomach this sphincter needs to relax and let it pass.

In addition to allowing food to enter the stomach, the lower esophageal sphincter prevents what has been introduced from going back, since if it did occur, reflux or even vomiting would occur.

4. Stomach

Perhaps many consider it the main part involved in digestion, although the two intestines, the liver and the pancreas take on great importance in this process.

Stomach is a sac in which food is mixed by the action of muscular movements with gastric acids, which break down food.

So food is reduced to elements much simpler than it was originally made, allowing these nutrients to be easily absorbed in later phases of the digestion.

When this action has already been carried out, the stomach empties, moving the digested food into the chyme, located in the small intestine.

5. Pancreas

This organ is responsible for producing juices much more powerful than saliva, with which carbohydrates, fats and proteins that are in food are broken down. Through some conduits, This juice is taken to the small intestine, where it will decompose.

6. Liver and gallbladder

The liver produces bile, with which some fats and vitamins present in food are digested.

Through specialized ducts, the bile is transported to the gallbladder, where it is stored until it is needed by the small intestine when digestion is taking place.

When a person eats, the gallbladder is squeezed out and releases bile through tubes that lead to the small intestine.

7. Small intestine

In this part, the foods that were already digested in the stomach are mixed with juices from the pancreas and liver, in addition to mixing them with their own intestinal juice.

The bacterial flora present in the intestine is responsible for producing specialized enzymes for the digestion of some carbohydrates. A diseased intestinal flora can be the origin of diarrhea and nutritional problems, which translate into health problems in the long run. The muscles of this organ are responsible for making food move forward.

In the walls of the intestine there are small hairs which absorb water and nutrients present in food, which have been reduced by the action of digestive fluids facilitating this phase. These are introduced into the bloodstream.

What cannot be used, either because it is not useful for the body or because it can become toxic to our body, is carried into the large intestine.

8. Large and straight intestine

Here what could not be digested, residual liquids and dead cells is treated for their subsequent elimination. In the large intestine, the water that remains in these residues is absorbed, causing them to harden, transforming into feces.

Through peristaltic movements these waste products are carried to the rectum, where they will be stored until they receive the signal to be defecated and fulfill the last function of the digestive system, egestion.

Bibliographic references:

• Keeton, W. and Harvey, D. (2016). Human digestive system. Encyclopedia Britannica.
• Moore, K.L. (1992). Clinically Oriented Anatomy. Baltimore: Williams & Wilkins.