The stomach is an organ without which it is impossible to conceive the process of digestion. A review of its parts and characteristics.
A human being at rest spends 60-70% of the energy from the diet only in breathing, pumping blood, thinking and digesting, which means a daily expenditure of up to 1,400 kilocalories. These data show that werequire a relatively fast and effective digestive system, since more than half of what we consume per day is burned only by existing.
Therefore, it is not entirely shocking to know that, if we completely extended the small intestine of an adult, it would occupy a whopping 6 meters with a total surface area of about 300 square meters, the same as a tennis court. The digestive system is characterized by its secretory capacity and its immense surface area, based on multiple folds and nooks and crannies.
Beyond all these data of great interest, we can not deny that thestomach is the organ that takes all the attentionwhen talking about the digestive process. Every human being knows that he has it and is able to notice when something is not right inside him, but do you know his physiology? If the answer is no, do not worry, because no one is born learned. We tell you below the 8 parts of the human stomach and their functions.
- You may be interested: “Stomach pain: causes and 7 home remedies to relieve it”
What is the stomach?
According to the National Cancer Institute (NIH), the stomach is defined as “an organ located in the upper abdomen that helps digest food by mixing it with digestive juices, turning it into diluted liquid.” To open your mouth, we show you some interesting facts about the stomach that contextualize it at a physiological and medical level. Let’s do it:
- Digestive juices work as a powdered detergent: both contain enzymes and fat solvents.
- In a stomach fit between half a liter and two liters of food.
- A steak can remain in the stomach for up to 6 hours: the digestion of proteins and fats is considerably slow and expensive.
- There are many animals that have neither stomach nor structures analogous to it. There are even people who live without a stomach.
- In the United States alone, more than 27,000 patients are diagnosed with stomach cancer each year.
With this seemingly random data series, we generate a general picture about the function and importance of the stomach in nature. Despite its exciting physiology (which we will describe below), we must emphasize that pathological processes in the digestive system are increasingly common, and stomach cancer is one of the most important. Epidemiological studies estimate that it is the fifth most common type of cancer worldwide.
What are the parts of the stomach?
Once we have made a brief tour of the functionality and disease of the stomach, we are prepared to see its parts. This organ is composed of 3 main physical parts: the fundus, the body and the antrum. In addition, it has two sphincters: the cardia and the pylorus. Started.
1. Cardia
Cardia is a term that refers to the opening that, in terrestrial vertebrate animals, allows regulated communication between the esophagus and the stomach. From a functional point of view, it is the place where the esophagus discharges its contents into the stomach.
The cardia has multiple smooth muscle fibers, which allow, through their coordinated relaxation, the phenomenon of swallowing. When these muscle tissues contract, the mixed food is prevented from returning gastric juices to the esophagus, a phenomenon known as reflux. GERD (Gastroesophageal Reflux Disease) is usually caused by incompetent cardia, that is, it is not able to close properly for unknown reasons.
2. Fundus
The fundus is a dilated region that formsa kind of vault that protrudes above the cardia. The smooth musculature is relatively thin in this portion, which is why the contractions produced here are quite mild. In general, the fundus stores only certain gas contents as it is the upper portion.
3. Body
It is the central or main portion of the stomach, that is, the largest area of all. The body is characterized by having the highest proportion of parietal cells, those responsible for producing and secreting gastric acid and intrinsic factor (a stomach glycoprotein).
Atrophic gastritis is a disease of the stomach that occurs when parietal cells atrophy, usually due to autoimmune attack phenomena. It can cause a special type of anemia due to a vitamin B12 deficiency. The fundic region is one that includes, as its name suggests, the fundus and the body.
4. Tooth
The antrum begins where the body ends and extends to the pylorus. It is the lower region of the stomach, which is why it dominates the smooth muscles. It is responsible for gastric secretion (although to a lesser extent than the body) and, due to the vigorousness of the peristaltic contractions that occur here, allows the emptying of food into the pylorus.
5. Pylorus
The pylorusis the lower valve that connects the stomach with the duodenum, and closes or opens, allowing or limiting the passage of the food bolus (in this case we already talk about chyme, since the food has joined with gastric juices) to the small intestine. The antrum and pylorus are commonly called distal stomachs.
6. Histological layers
This category is not about a part in itself, but about the description ofa cross-section of stomach tissue. It is necessary to know the number of histological “layers” that this organ presents to understand its full functionality. Let’s do it:
- Mucous layer: the most important of all, since it presents multiple folds, pits and crypts with cell bodies where mucus and gastric acids are produced, among other substances.
- Tunic submucosa: formed by connective tissue, this layer is riddled with blood vessels, lymphatic vessels and nerve endings.
- Muscle layer: here are three layers of smooth musculature, which create peristaltic movements that allow the emptying of the stomach.
- Serous tunic: surrounds the stomach in all its extension and protects it and delimits it from the rest of the organs.
7. Curves: major curvature and minor curvature
It should be noted that thestomach has two large curves that form the inner and outer edges, the so-called major curvature and minor curvature, respectively. The first one responds to the region of the body of the stomach located in the left part of the body. Therefore, it forms the outer edge of this organ. On the other hand, the smallest curvature is the one that is located in the most “right” part of the body, thus forming the inner edge of the stomach.
8. Gastric folds
Again, we are not facing a part in itself, but we are talking about a physiological characteristic common to the whole stomach. The mucous layer of this organ has multiple gastric folds, which have the functionof multiplying considerably its available surface.
It should be noted that these folds disappear when the stomach is full or distended, but reappear again when the emptying process begins. These folds also have a series of holes, called foveolae, where the gastric glands producing acid and other substances flow.
Some diseases are characterized by thickening of the gastric folds, an event that can be caused by benign causes (hypertrophic gastritis, Ménétrier’s disease, Zollinger-Ellison syndrome, lymphoid hyperplasia and amyloidosis) or for reasons with a worse prognosis (adenocarcinoma, lymphoma or metastatic tumors).
Summary
As you may have read along these lines, the stomach is a seemingly simple organ that has many secrets to discover. While it is true that the fundus, the body and theantrum are the 3 most significant parts of this very important organ, both the valves and the different histological layers and gastric folds play an essential role in maintaining the functionality of the stomach correctly.
To the classic question “what do you do?” I always answer “basically I am a psychologist”. In fact, my academic training has revolved around the psychology of development, education and community, a field of study influenced my volunteer activities, as well as my first work experiences in personal services.