Digestive system: anatomy, parts and functioning
Contrary to what many people think, the digestive process does not just involve mixing food with the gastric acids in the stomach.
Both chemical and physical actions are carried out, starting 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 , which organs make it up and which functions each of them performs.
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 transforming food into nutrients that can be used by the body so that it can maintain its physiological functions.
Its main function is to extract the nutrients that are present in 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. Inside the cells, metabolic reactions take place that give energy and substances to maintain the cell structure.
In addition to nourishing at the cellular level, the digestive system takes care of getting rid of those substances that are not beneficial for the body , whether they are non-helpful or toxic and pathogenic substances. These elements are the ones that will compose the faeces, which will be eliminated through egestion.
Below we explain all the parts that make up this system, as well as presenting them in the order in which the digestion takes place and what their fundamental functions are during this process.
Digestion: the path of food within us
This is the route that food takes to pass through the nervous system.
1. Mouth
The mouth is the entrance door of food to our body and the place where the first phase of digestion takes place: ingestion .
Here the food is reduced by chewing, breaking it down by physical action and transforming it into smaller parts.
In addition, saliva, a liquid containing enzymes that break down food starches, is secreted in the mouth. This is the first chemical reaction that food is subjected to once it has been incorporated into the body.
The tongue is responsible for pushing the food down the throat . Before reaching the oesophagus, it is necessary to prevent the food from ending up in the wrong way 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 the food has been swallowed, it travels down the esophagus. This is a tube through which food is carried to the stomach . This requires the action of some muscles, which perform movements called peristaltic.
3. Lower esophageal sphincter
It is the part that separates the esophagus from the stomach, being the entrance door to the latter. In order for food to be introduced into the stomach it is necessary for this sphincter 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 backwards, as this would cause reflux or even vomiting.
4. Stomach
Perhaps many consider it the main part involved in digestion, although the two intestines, the liver and the pancreas, become very important in this process.
The stomach is a sac in which food is mixed by the action of muscle movements with gastric acids , which break down food.
Thus the food is reduced to much simpler elements than it was originally made, allowing these nutrients to be easily absorbed in later phases of digestion.
When this action has been performed, the stomach empties, moving the digested food to the chyme , located in the small intestine.
5. Pancreas
This organ is responsible for producing much more powerful juices than saliva, with which the carbohydrates, fats and proteins in food are broken down. This juice is taken through channels to the small intestine, where it is broken down .
6. Liver and gallbladder
The liver produces bile, which is used to digest some fats and vitamins in food.
Through specialized ducts, 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 and releases bile through tubes that carry it to the small intestine.
7. Small intestine
In this part, the food that had already been digested in the stomach is mixed with juices from the pancreas and liver, as well as with its own intestinal juice.
The bacterial flora present in the intestine is responsible for producing enzymes specialised in the digestion of certain carbohydrates. A sick intestinal flora can be the origin of diarrhoea and nutritional problems , which translate into long-term health problems. The muscles of this organ are responsible for making the food move forward.
In the walls of the intestine 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 taken advantage of, either because it is not useful for the organism or because it can become toxic for our body, is taken to the large intestine .
8. Large straight bowel
Here what has not been able to be digested, residual liquids and dead cells are treated for later elimination. In the large intestine, the water remaining in these residues is absorbed, causing them to harden, transforming them into faeces.
By means of peristaltic movements these waste products are taken to the rectum , where they will be stored until they receive the signal to defecate and fulfil 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.