HOW DOES THE STOMACH WORK? Let’s get to know it a little better . . .
The stomach is a quite large hollow organ of the digestive system with a particular dilated structure, like an elastic bag.
The food, that has already started the first phase of digestion through the chewing in the mouth, passes into the esophagus and it reaches the stomach through the valve of the cardias. Here it is stored, mixed and further digested by turning into a semi-liquid mass, the chyme, which continues its journey into the small intestine.
Therefore, the function of the stomach is to store, to digest (especially the protein and the lipid component) and to sterilize the food that it is transformed into chyme and transferred to the small intestine.
All this work is possible thanks to its elastic structure rich in numerous internal folds (pleats) and to the presence of more than 35 million of glands that cover it all internally!
These glands produce the gastric juice: a viscous and extremely acid yellowish liquid consisting of a mixture of glandular secretions. Among these, the pepsin is responsible for the protein digestion, the lipases for the fats and the hydrochloric acid helps the protein digestion, the elimination of possible unwanted guests, the bacteria,entered with the food and it is essential also for the absorption of vitamin B12 (see the upcoming article on the Intrinsic Factor)
The gastric juices are extremely acid!! Due to their very low pH value they can corrode virtually any material. You know that during the secreting activity of the stomach its pH can reach even the value of 1!
. . . THEN, HOW THE STOMACH NORMALLY PROTECTS ITSELF FROM THESE ACIDS?
For many years, scientists wondered how the stomach could protect itself from the corrosive effect of the gastric juices produced by its cells, capable of leaving indelible marks even on very resistant surfaces such as marble.
Only recently it has been understood the mechanism: the defensive barrier of the stomach that, if altered, it can also cause many disorders such as gastritis and gastroduodenal ulcer.
The stomach protects itself from its own acids with an inner lining called mucosal-gastric barrier. This consists of a mucous layer made by very viscous mucoproteins and bicarbonate droplets, both produced from the superficial cells of the stomach. The set of mucus and bicarbonate together creates a barrier able to protect against the acids’ attack, as it changes the pH value. Indeed, pH value is very low, around 1.5-2, in the lumen of the stomach (green in the image below) while it reaches the value of about 7.0 near the viscous gel (in blue in the figure), ie practically the physiological value.
Therefore, in healthy conditions, the cells of the gastric epithelium (in pink in the figure) remain protected from the erosion effect of the stomach acids.
Indeed, the well-being and the proper functioning of the stomach precisely depend on the body’s ability to keep this mucosal barrier intact.
It may happen that this barrier undergoes more or less important alterations due to different possible external (environmental) or internal reasons. This determines the activation of inflammatory processes that occur in the body such as burning, gastritis, ulcer, despair ….
If you are suffering from some of these disorders, there is good news. I would like you to know that there is much you can do to deal with these fastidious and even painful conditions!
Follow me in the next article: we will talk about the causes of gastritis and stomach pain and how to improve these symptoms through an adequate nutrition and lifestyle.
If you feel good your stomach feels good, too!
See you soon!