Mediators

Neurotransmitters: key players in the transmission of nerve impulses

Mediators are substances formed in nerve endings and play a key role in the transmission of nerve impulses from one nerve cell to another, as well as from the nerve ending to a working organ, such as a muscle fiber or glandular cell. The process of transmission of a nerve impulse begins with the occurrence of a nerve impulse upon irritation of any organ or tissue in the nerve endings. The nerve impulse is transmitted along sensory fibers to the central nervous system (spinal cord and brain), and then through motor nerves is sent directly to the muscles, causing their response.

In order for a nerve impulse to excite the nerve cells of the brain and then switch from the motor nerve ending to the muscle, a chemical intermediary is needed - a mediator. The experimental study of mediators began with the discovery by the Austrian physiologist and pharmacist Otto Lewy in 1921 of the fact that a solution bathing an active preparation of an isolated frog heart can affect another similar preparation in a manner similar to direct irritation of the heart.

Electron microscopy studies have shown that mediators are contained in numerous vesicles formed at the site of contact between nerve endings and the nerve cell body, in the so-called synapses. During the process of nervous excitation, some of the synaptic vesicles burst, and their contents interact with the membrane of a nerve or muscle cell, causing excitation of this cell. It has been established that the release of mediators occurs not only during excitation, but also during inhibition of all parts of the central and peripheral nervous system.

There are several different types of neurotransmitters that play different roles in the transmission of nerve impulses. For example, the endings of the vagus nerve contain acetylcholine, which plays an important role in transmitting impulses to the muscles. The endings of the sympathetic nervous system contain norepinephrine, which is involved in the regulation of cardiac activity and vascular tone. In addition, other mediators were discovered, such as histamine and bradykinin, which cause dilation of capillaries, serotonin, which constricts blood vessels and depresses the central nervous system, and others.

Research on mediators has yielded important results for the clinic. It turned out that in a number of diseases of the nervous system and in some poisonings, the formation, action or breakdown of mediators can be disrupted, which can lead to serious disorders in the body. Based on this, new methods of treating such diseases were developed and put into practice.

The influence of a number of substances that interfere with the transmission of nerve impulses using mediators has also been discovered. Previously known examples of such substances were curare and atropine, which were used for anesthesia and immobilization during surgical operations. Now, based on this mechanism of action of curare-like drugs, new drugs have been created that are widely used in surgery, anesthesiology and other fields of medicine.

However, despite all the advances in the study of mediators, much remains unknown. For example, it is not known exactly how neurotransmitters interact with the membrane of a nerve or muscle cell, and how their breakdown occurs. It is also unknown how mediators are involved in more complex processes such as learning and memory.

In general, neurotransmitters are key players in the transmission of nerve impulses and play an important role in the functioning of the body. Studying neurotransmitters and their interactions with other substances can lead to new treatments and improve our overall understanding of how the body functions.