I.P. Pavlov is one of the founders of the physiology of the digestive system. One of the most valuable achievements of the physiologist is the creation of the foundation for further scientific research of the digestive tract. The physiologist, who was later awarded the Nobel Prize, applied the most innovative methods. A high level of skill was already apparent in Pavlov’s first research.
Discoveries in Physiology and Psychology
Pavlov’s method, with the help of which the physiologist made his famous experiments with dogs, is known to every student. Thanks to his most famous experiments, the scientist was able not only to study the composition of digestive juices, which laid the foundations of modern physiology, but also to draw important conclusions regarding the functioning of the central nervous system. That is why the Pavlov method in psychology is no less important than in the field of physiology and medicine. Relying on the concept of a conditioned reflex he discovered, the scientist was able to explain the most complex processes that take place in the human cerebral cortex.
Pavlov was a follower of Sechenov. However, when the latter had to leave Petersburg, the great Russian physiologist continued his studies with I.F. Zion, who taught him the virtuoso technique of conducting operations. For more than a decade, Pavlov devoted himself to being able to install fistulas (or holes) in the walls of the esophagus of animals.
Starting to study the salivary glands, Pavlov possessed the best research base out of all the physiological issues that he dealt with. However, the theoretical conclusions of that time contained many erroneous provisions. For example, it was believed that reflex salivation completely depends on the excitation of receptors located in the oral cavity. Pavlov's method, which was called the chronic experiment (such when the animal remained alive after the experiments). He allowed to advance the physiology and medicine of that time to a significant level.
Innovative way
In order to be able to study the composition and effect of the digestive juices, they had to be taken out in some way in their pure form. Obtaining gastric juice by the Pavlov method has become one of the most advanced and progressive steps in research on the physiology of internal organs. Not a single physiologist could do this before I.P. Pavlov. For example, the following operation was often used: a gastric cavity was opened in a dog and a pancreatic duct was found. A tube was inserted into it, and in a few minutes, while the animal was still alive, the researchers received as much as drops of gastric juice. Pavlov was against such operations, since the material obtained by this method was contaminated. These data in no way could advance medical science.
Features of the physiologist's experiments
Pavlov’s method was fundamentally different from the attempts of his predecessors to obtain material for research. Having found the duct of the pancreas, the scientist separated it from the duodenum. Then he sewed a piece of the intestinal wall to the edges of the wound on the surface of the abdomen. Now the gastric juice was being worked out - into a specially set funnel.
If the animal had healthy other glands, this did not affect life activity - for several years the dogs were completely healthy and suitable for experiments. The obvious advantage of all Pavlov's research methods was the ability to preserve the life and health of the experimental animal. I.P. Pavlov knew the general property of life - for the most part, redundancy takes place in all living organisms, the same function is provided in different ways, and because of this, the body almost always has reserve opportunities for survival.
Merits of a scientist
Pavlov established constant fistulas for animals. With their help, it was possible to constantly monitor the activity of a certain internal gland. For the method of Pavlov was called fistular. Using this method, the physiologist was able to collect the digestive juices produced in various phases of the food processing process. The role of the physiologist in the study of the activity of the digestive glands cannot be overestimated - scientists often call this section of physiology the “Russian chapter”, and IP Pavlov himself was awarded the highest award — the Nobel Prize in 1904.
Another discovery
Pavlov's method also allowed us to study the formation of conditioned and unconditioned reflexes. Pavlov noted that the dog’s gastric juice is secreted not only by the sight of food, but also when the animal hears the noise of the steps of the person who brings it. So the scientist began to study the vital processes of the brain. Moreover, reactions of this kind could be developed in animals not only in response to the noise of steps, but also to the inclusion of light, the ringing of a bell, various smells, etc.
Types of Reflexes
The physiologist divided all possible body responses into two categories. He called the innate reactions unconditional, and those that were acquired in the process of life - conditional. The first category includes protection from enemies, the search for food, and also quite complex actions - for example, building a nest. Unconditioned reflexes are inherent in every living organism from birth. And the execution of the commands that the animal receives from the trainer belongs to the category of conditioned reflexes.
They can exist for quite a long time, but sooner or later they can disappear, slow down. At the same time, the physiologist found that the inhibition process can be external. For example, the dog has already developed a salivary reflex to the inclusion of light. If, then, the inclusion of the light bulb is accompanied by an unusual noise for the animal, then the conditioned reflex in some cases may not occur. For this reason, in the institute where Pavlov conducted his experiments, a special department was built - the “Tower of Silence”, in which the walls were very thick and did not allow extraneous sounds.
Signaling systems
The researcher identified two signaling systems that are inherent not only to animals, but also to humans. People, like animals, perceive signals from the outside world. This type of physiologist called the first signaling system. However, a person is significantly different from his smaller brothers by a socially conditioned second signaling system - speech. Without communication with other people, this type of system in humans does not develop. The research methods of I.P. Pavlov were widely recognized not only in physiology and medicine, but also in psychology and pedagogy.
Research
For example, Pavlov managed to make an important conclusion: the secretion of salivation is not always the same. This process varies, and is influenced by several factors: firstly, it is strength, nature, as well as the number of external stimuli; and secondly, the directly functional significance of the saliva produced (it can be digestive, hygienic, or protective). After analyzing the results obtained during the experiments, Pavlov made the most important conclusion: the subtle variability in the work of the salivary glands is dictated by the different excitability of the receptors in the oral cavity to various irritants. These changes are adaptive. Later, the physiologist found that this conclusion is also true for another type of saliva secretion - mental secretion.
Merits of the physiologist
Pavlov’s work methods are rightly called advanced for another reason: one of the most important achievements of a physiologist is the discovery of the leading role of the nervous system in a living organism. It is the nervous system that plays a paramount role in the work of various digestive glands, the regulation of other internal organs. This teaching was later called nervousness. The knowledge gained by Pavlov is also used in the modern world. It is on the basis of this information that various medicines are used that are used to treat the digestive system, and recommendations are also given regarding proper nutrition.
For the first time, the scientist voiced his research in the field of physiology of higher nervous activity at the Madrid report written in Russian. In total, the scientist devoted a total of about 35 years to the study of the physiology of the nervous system.
Getting clean material
What method did Pavlov use to establish the composition of pure gastric juice? If we talk about terminology, then his method got its name - "imaginary feeding method." It became possible to study pure gastric juice only after the application of this experiment by I.P. Pavlov and E.O. Shumova-Simanovskaya. It was first held in 1889. Another operation was attached to the fistula overlay - esophageal transection. But at the same time, the esophagus was not completely cut. Only two-thirds of its thickness was subject to dissection - the edges were sewn to the surface of the cervical muscles.
Science and animal life
A huge amount of controversy over their ethics still causes the Pavlov method. Dogs at the same time aroused admiration from the great physiologist. Pavlov considered them perfect animals and sincerely mourned for every life that had to be put on the altar of scientific research. The scientist tried to minimize the suffering of experimental animals. He resorted to euthanasia only in those cases when they no longer had a chance.