We explain what the digestive system is, its functions and the organs that make it up. In addition, the most common diseases of this.
What is the digestive system?
It is known as the digestive system. 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 carries out this function.
During digestion or the digestive process, the different types of nutrients found in the foods consumed (carbohydrates, lipids and proteins) are transformed into simpler units, thanks to the different digestive enzymes. Under these conditions, the most basic 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, in which numerous organs and parts of the body are involved and is essential for life given that human beings (like all animals) are heterotrophic, and therefore we can only incorporate the organic matter we need through food.
See also: Circulatory system
Functions of the digestive system
The digestive system performs various functions, but the main ones are four: food transportation, secretion of digestive juices, nutrient absorption 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, passing through the stomach and then reaching the intestines.
- Secretion of digestive juices Throughout the digestive tract, food receives secretions from different organs, which allow its chemical digestion. Already 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 chemically digested, that is, reduced to its minimum usable units.
- Nutrient absorption. Once the food has been digested (reduced to its simplest forms), the nutrients are absorbed in the small intestine, then entering the blood to be distributed throughout the body. For its part, water and some salts are absorbed in the large intestine.
- Egestion of feces. Once the nutrients have been extracted from the food, the waste material (the indigestible remains that were not used) must be expelled from 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 tube (which begins in the mouth and ends in the anus and measures around eleven meters) and the adjacent glands (salivary glands, liver and pancreas). Next, let's see which organs are part of this device 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). Additionally, in the mouth there are salivary glands that produce and secrete saliva. This secretion has multiple functions: it moistens the food and also contains enzymes (which begin chemical digestion) and bactericidal substances.
- Pharynx. It is a tube-shaped structure that is part of both the digestive and respiratory systems: it connects the mouth with the esophagus (letting food pass through the digestive tube) and the nasal passages with the larynx (letting air pass through the digestive tract). 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 tube, which transports food from the mouth to the stomach, crossing the neck, thorax and abdomen, and passing through a hole in the diaphragm.
- Stomach. Food accumulates in this organ. The cells that make up the stomach secrete gastric juices, composed mainly of pepsinogen, an enzyme precursor, and hydrochloric acid (HCl). This substance gives acidity to the medium, allowing the activation of pepsinogen into pepsin (a digestive enzyme that degrades proteins) and also functioning as a bactericide. The internal 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 with the large intestine. The small intestine is full of villi and is the place where food is digested and nutrients are absorbed. This body is divided into two parts. The first portion is the duodenum, which measures between 25-30 cm and is where the secretion of intestinal juice 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 the natural habitat of bacteria that synthesize vitamins necessary for the body.
- Pancreas This gland is in contact with the intestine and pours its pancreatic juice into the duodenum, which contains different enzymes essential for digestion. On the other hand, the pancreas also synthesizes and releases hormones into the blood that regulate sugar metabolism, such as insulin, which allows glucose to enter 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 accumulates in the gallbladder and from there passes into the duodenum.
- Year. The anal opening is where feces or fecal matter are expelled to the outside of the human body, through controlled movements of the anal sphincter.
Diseases of the digestive system
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 not proper elimination of feces.
- Indigestion The consumption of food in poor 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 mucosa (gastritis) and, in more severe cases, to ulcers and internal 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.
