What is the Digestive System?

What Does Digestive System Mean

We explain what the digestive system is, its functions and organs that compose it. In addition, the most common diseases of this one.

It is a complex mechanism, involving many parts of the body.

What is the digestive system?

The digestive system is known as the set of organs that are responsible for the digestive process , that is, the transformation of food so that it can be absorbed and used by all the cells of the body. In addition to humans , most higher animals have a digestive system that performs this function.



During the digestion or digestive process, the different types of nutrients found in the food consumed (carbohydrates, lipids and proteins ) are transformed into simpler units, thanks to the different digestive enzymes . Under these conditions, the most elementary usable parts of the nutrients can be absorbed and then transported by the blood to all the cells of the body, where they are used to obtain energy and carry out all the functions essential for the support and development of life. .

The functional process of the digestive system includes all the events that take place, from the entry of food into the mouth, to the expulsion of feces (indigestible remains) through the anus, through the absorption of nutrients through the intestinal walls. It is a long process, which involves a set of complex mechanisms, involving numerous organs and parts of the body and which is essential for life , since human beings (like all animals) are heterotrophs , and therefore so much so that we can only incorporate the organic matter that we need through food .

See also: Circulatory system

Functions of the digestive system

The digestive system fulfills several functions, but the main ones are four: transport of food , secretion of digestive juices , absorption of nutrients and excretion of feces .

  • Food transportation. Food enters the mouth, where it is crushed by the teeth and moistened by saliva, and becomes the bolus, which is pushed into the esophagus with the help of the tongue. Then, through peristaltic movements (a type of muscle contraction and relaxation movement), food continues to move through the digestive tract, through the stomach, and then into the intestines.
  • Secretion of digestive juices. Throughout the digestive tract, food receives secretions from different organs, which allow its chemical digestion. In the mouth, the salivary glands secrete an enzyme that begins the transformation of sugars. The chemical digestion process continues in the stomach (thanks to the presence of gastric juices secreted there) and in the first portion of the small intestine (duodenum), where partially digested food is subjected to the action of bile and intestinal juices. and pancreatic. The enzymes and other substances present in all digestive juices allow food to be completely digested chemically, that is, to be reduced to its minimum usable units.
  • Nutrient absorption. Once the food is digested (reduced to its simplest forms), the nutrients are absorbed in the small intestine, then passing into the blood to be distributed throughout the body. For its part, water and some salts are absorbed in the large intestine.
  • Egestion of stool. Once the nutrients are extracted from the food, it is necessary to expel the waste material (the indigestible remains that were not used) out of the body, which is done through the end of the digestive tract.

Organs of the digestive system

The digestive system is made up of the digestive tract (which begins in the mouth and ends in the anus and measures around eleven meters) and the adjoining glands (salivary glands, liver and pancreas). Next, let's see what are the organs that are part of this apparatus and the functions they perform.

  • Mouth and salivary glands. The mouth or oral cavity is the place where food enters the body. This organ contains different structures , such as the teeth (which allow chewing) and the tongue (which facilitates swallowing). In addition, in the mouth are the salivary glands that produce and secrete saliva. This secretion has multiple functions: it moistens the food and also contains enzymes (which start chemical digestion) and bactericidal substances.
  • Pharynx. It is a tube-shaped structure, which is part of both the digestive and respiratory systems : it connects the mouth with the esophagus (allowing food to pass through the digestive tube) and the nasal passages with the larynx (allowing air to pass into the lungs). The pharynx has a structure called the epiglottis, which acts as a valve separating the digestive and respiratory tracts.
  • Esophagus. It is a muscular conduit, which carries food from the mouth to the stomach, through the neck, thorax and abdomen, and passes through a hole in the diaphragm.
  • Stomach. Food accumulates in this organ. The cells that make up the stomach secrete gastric juices, composed primarily of pepsinogen, an enzyme precursor, and hydrochloric acid (HCl). This substance gives acidity to the environment allowing the activation of pepsinogen in pepsin (digestive enzyme that degrades proteins) and also functions as a bactericide. The inner walls of the stomach are lined with a mucosa that protects them from the action of acid.
  • Small intestine. This first portion of the intestine, which measures between 6 and 7 meters in length , begins in the duodenum and reaches the ileocecal valve, where it joins the large intestine. The small intestine is full of villi and is the place where food is finished digesting and nutrient absorption occurs. This body is divided into two parts. The first portion is the duodenum, which measures between 25-30 cm, which is where intestinal juice secretion occurs and secretions from the pancreas and liver are received. The second portion is the jejunum-ileum, where the absorption of nutrients occurs once they have been digested.
  • Large intestine. It is the rest of the intestine, which culminates in the rectum and measures between 120 and 160 cm in length. This organ fulfills several very important functions for the body: it is where feces are formed, but it is also the portion of the digestive system where water and salts are reabsorbed . In addition, the large intestine is a natural habitat for bacteria that synthesize vitamins necessary for the body.
  • Pancreas. This gland is in contact with the intestine and spills its pancreatic juice into the duodenum, which contains different enzymes essential for digestion. On the other hand, the pancreas also synthesizes and releases into the blood hormones that regulate the metabolism of sugars, such as insulin, which allows the entry of glucose into the cells.
  • Liver and gallbladder. The liver is the largest organ in the body (it weighs a kilo and a half) and has multiple and varied functions. This organ produces bile, a substance necessary for the digestion and absorption of fats (allows their emulsification). Bile collects in the gallbladder and from there it passes into the duodenum.
  • Year. The anal opening is where feces or fecal matter is expelled out of the human body, through controlled movements of the anal sphincter.

Diseases of the digestive system

Intestinal parasites are common in people living in poverty.

There are various diseases of the digestive system. Some of the main and most frequent are:

  • Infections Product of bacteria or viruses entering the intestine that come from contaminated water or food. They can cause diarrhea, bloody stools or rectal mucus, as well as severe intestinal pain.
  • Parasites Intestinal parasites are common in rural populations or in people living in poverty and are transmitted through contaminated food or water. The parasites can then migrate to other regions of the body and perpetuate the cycle if there is no proper elimination of the feces.
  • Indigestion. The consumption of food in bad condition or contaminated with toxic or harmful substances can generate an intestinal reaction very similar to allergic reactions, with colic and usually diarrhea.
  • Gastritis and ulcers. The action of gastric juices and the constant consumption of irritants ( alcohol , cigarettes, citrus fruits, etc.) can lead to redness and inflammation of the stomach lining (gastritis) and, in more severe cases, to internal ulcers and sores.
  • Cancer. Cancer of the duodenum, colon, liver or pancreas are known and aggressive forms of malignant tumors, associated with certain eating habits and which also have a high hereditary component.
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