Digestion is a process that we all carry out unconsciously, the body itself does this at a reflex level. This process is complicated, therefore the question of the curious person “What is digestion?” Is justified. From the doctor’s point of view, this is a food processing process, physical and chemical. As a result, it becomes possible to absorb substances as well as remove waste.
Digestive organs - communicating hollow organs, supplemented by glands, which help break down chemical bonds in substances. For example, potato carbohydrates and bread carbohydrates are in the form of starch, they cannot be absorbed until the starch molecules are broken down to glucose. The protein of meat is also unable to assimilate by itself - it is necessary to decompose it into its constituent amino acids (from which the body can build its own protein). Fats alone cannot be inside the body’s environment - only after digestion results in fatty acids and glycerin.
The physiology of digestion is such that substances that, although they are inside the body, are not in the body’s environment. To do this, they have to undergo many transformations. And then absorption occurs through the thin mucous membranes. Digestive organs also include the liver, salivary glands, and pancreas. In addition, in the wall of the digestive organs there are glands that produce substances necessary for digestion. All walls are covered with mucus, thus reducing the likelihood of injury to the delicate membranes.
The teeth are mechanically processed, then it is mixed with saliva. Three pairs of large glands and many small ones secrete saliva. This fluid contains organic components, minerals, and decay products of white blood cells. But the main thing is that it contains two enzymes - ptyalin (breaks down starch) and maltase (breaks down sugar from rye, barley, etc.). From the mouth, through the throat, food enters the esophagus.
The esophagus is a tube that can be called quite straight. It is covered with stratified squamous epithelium. These cells are constantly updated, as they are very easy to injure. Division occurs in the deeper layers, while the outer ones are desquamated and lowered into the stomach with food. In the submucosa there is a small amount of glands - the glands of the esophagus. Near the stomach, they are similar in secretion to the stomach, they are called cardiac glands. At the beginning of the esophagus there are many striated muscles, but in the lower third there are only smooth muscle fibers. The swallowing process begins consciously, but then the reflex response is turned on. After the esophagus, digestive organs such as the stomach and intestines take up food.
The stomach works like an excellent mixer thanks to its well-developed muscles. In this organ, protein breakdown begins with the help of the pepsin enzyme, bacteria are killed by hydrochloric acid. As a result of digestion in the stomach , a semi-liquid evenly ground content is obtained - chyme. Some salts, water, alcohol, and some medicines are absorbed from it. The stomach produces antianemic factor molecules.
After the food enters the small intestine. Its length is an average of six meters. The first 30 cm is the duodenum. It is attached to neighboring organs and goes around the head of the pancreas. Then it goes into the skinny and then the ileum. In the small intestine , the digestion process is completed, and also the digestive products are selectively absorbed into the blood and lymph. In the small intestine there are special formations - villi, which greatly increase the absorption area. Ducts from the liver (bile) and pancreas flow into this section of the intestine. As a result, it is here that carbohydrates, fats and proteins are finally digested and assimilated. Moreover, fats go directly to the lymph, which then connects to the blood.
In the large intestine, the digestion of residues is completed, but putrefactive bacteria are already “for themselves”. Water is absorbed, and the remnants of the food acquire the consistency of feces. In the final section, the rectum, waste products are waiting to be removed during a bowel movement. So the process of digesting food ends. All digestive organs are important in it, only their well-coordinated work is able to help the cells of the body renew due to the availability of building materials for the cells.