Where is the vasomotor center? Its meaning

The vascular system of the body is very important. Because of the arteries and veins, blood and oxygen are delivered. Without this feature, people could not live. Responsible for this function of the body vasomotor center. Like all regulatory mechanisms, it is located in the brain. Its damage is very dangerous and often incompatible with life. After all, thanks to the vasomotor center, blood is distributed to the organs. It also partially regulates cardiac activity. Despite the autonomy of the myocardium, control of the nervous system is still necessary.

The concept of vasomotor center

The concept of "vasomotor center" is explained thus: it is an anatomical formation located in the brain. Nevertheless, this term should be considered more widely. First of all, this is not one organ, but a set of formations consisting of nerve tissue. Each of the parts is responsible for certain functions. Nevertheless, they all work together to ensure the activity of the cardiovascular system. These sections of the vasomotor center are interconnected not only functionally, but also anatomically. That is, through nerve fibers. For the first time, the regulation of the vascular system became known in the late 19th century. When carrying out experiments on animals, the scientist Ovsyannikov discovered that when cutting the nerve tissue located below the hills of the quadruple, changes in blood pressure occur. The physiologist made the following conclusion: a violation of this structure of the brain causes the expansion of some vessels, and the constriction of others. After this, the regulatory function began to be actively studied.

Location of the vasomotor center

It is believed that the vasomotor center is in the medulla oblongata. But if you take into account all the structures that affect the regulatory function of the blood supply, then this judgment is not entirely correct. Since the nerve fibers of the vasomotor center originate from the spinal cord, and its last link is the cortical layer. The first are axons - the processes of the cells. The neurons themselves are located in the three upper lumbar and all thoracic segments of the spinal cord. Their exact location is the side horns. Because of their location, they are called spinal vasoconstrictor centers. However, this name is incorrect, since the fibers are not capable of influencing apart from the other links. The vasomotor center of the medulla oblongata is located in the 4 ventricles. It is an accumulation of nerve cells. A more accurate localization of the vasomotor center is the lower and middle part of the rhomboid fossa. Part of the neurons are located in the reticular formation.

The following departments, related to the regulatory links of the center, are the hypothalamus and the middle brain. There are nerve fibers responsible for changes in vascular activity. The final link is the cortex of the brain. The pre-motor and orbital divisions are more involved.

Sosudodvigatelny center: physiology of the organ

If you imagine all the links of the vasomotor system from the bottom up, you should start with the neurons that are in the spinal cord. From them depart sympathetic preganglionary axons (fibers). These links can not independently regulate their tone, but they transmit impulses from other nerve cells to the vessels. The scientist Ovsyannikov learned about their significance for the first time, thereby making a great discovery in physiology. He found that the division of the brain and spinal cord is accompanied by a drop in blood pressure. Nevertheless, after a while the blood pressure rises again (below the initial level) and is independently maintained by the preganglionic fibers. In the medulla oblongata is the nerve center - the vasomotor. It is he who is responsible for the regulation of the spinal cord. His physiology is as follows: neurons in this center are divided into 2 types. The first are responsible for the pressor function (narrowing of the vessels). The second group leads to a relaxation of the endothelium. It is believed that the neurons responsible for vasoconstriction prevail in quantity. Cells in the middle brain can cause an increase in blood pressure. Neurons of the hypothalamic region, on the contrary, act as depressors, that is, lead to a relaxation of blood vessels. Most of the nerve fibers pass through the center, located in the medulla oblongata. In addition, part of the axons connect the spinal cord and the hypothalamus directly. The anterior region of the cerebral cortex affects both the enhancement and inhibition of the activity of neurons located in the underlying links.

Division of the vasomotor center into departments

Taking into account the fact that several parts of the nervous system are regulated, the following sections of the vasomotor center can be distinguished:

1. Spinal cord. In the lateral horns of the thoracic and lumbar segments are preganglionic nuclei. From them axons - fibers leave.
2. Directly vasomotor center. In this department, the neurons are responsible for the relaxation of the endothelium and vasoconstriction.
3. The middle brain. The cells present in this compartment are capable of causing a narrowing of the vascular wall.
4. Hypothalamic area. The neurons responsible for relaxation of the vascular tissue are connected both with the center itself and separately with the cells of the spinal cord.
5. Area of the bark. Despite the fact that the bulk of the neurons are located in the anterior region, other regions of the brain may also be affected.

Despite the presence of 5 departments, physiologists divide the vasomotor regulation by only 2 links. These include the fibers of the spinal cord and the bulbar region. In its composition, all other nerve cells that affect the tone of the vessels. Both classifications are considered correct.

Vessel-motor center: functions of the body

As is known, the main purpose of the vasomotor center is the regulation of the tone. Each of its departments performs its own function. Nevertheless, switching off at least one link leads to disruption of the operation of the blood vessels of the whole organism. Allocate the following functions:

1. Carrying out pulses (signals) from the cortical and medulla oblongata to the periphery. This refers to the influence of neurons on blood vessels, blood supply organs. This function is performed thanks to spinal preganglionic fibers.
2. Maintenance of vascular tone. In normal operation of each department, blood pressure is maintained at the proper level.
3. Relaxation and narrowing of blood vessels. Direct influence is exerted by the center located in the medulla oblongata.
4. Ensure adequate blood flow and distribution to each organ.
5. Thermoregulation. This function is carried out through changes in the lumen of the vessels. Their expansion is observed in a warm environment, and narrowing occurs at low temperature.

Connection of the center with the heart

In addition to the fact that the vasomotor center is responsible for the narrowing and expansion of the endothelial tissue, it also affects the cardiac muscle. This involves the cells located in the lateral part of the fossa of the 4th ventricle. It is known that innervation of the heart is due to sympathetic fibers. They are pulses from the medulla oblongata. As a result, activation of cardiac activity takes place. This is manifested by tachycardia. In the weakening of the heart, neurons of the vasomotor center also participate. They are located in the medial part. From there, the signals go to the dorsal nuclei of the vagus nerve. Despite the fact that one function of the heart muscle is automaticity, its work is impossible without the involvement of the brain.

Regulation of the vasomotor center

The cortical structures can influence the neurons of the vasomotor center located in the medulla oblongata. After all, they are the main mechanism for the regulation of all the underlying departments. Neurons of the cortex can cause both a decrease and an increase in the activity of the vasomotor center. In addition, there is a reflex regulation. It is carried out from the sinuses of the carotid arteries and from the aortic arch. This is due to mechanoreceptors. From their surface, impulses rise along the vagus and depressor nerves to the vasomotor center. In this case, the activity of the depressor part of this department is intensified. As a result, the vessels relax and lower blood pressure. Also, vasodilation is caused by the activation of the nuclei of the vagus nerves.

Changes in vasomotor center tone

Under the influence of various factors, regulatory disturbances occur. As a result, the tonus of the vasomotor center changes. Under normal conditions, this is accomplished through reflex regulation. In pathologies, there is a violation of tone. An example are various vascular diseases, atherosclerosis, obesity. Also, the decrease or increase in tone can be regulated by the influence of medications (antihypertensives, vasopressors).

The effect of chemicals on the vascular center

A direct influence on the regular mechanisms of the vascular system can be provided by chemicals in the body. An example is carbon dioxide, which accumulates in the blood with a lack of oxygen (asphyxia). Under the influence of this substance, the vasomotor center is stimulated. In severe cases, a prolonged lack of oxygen can lead to his paralysis.