Blood supply to the brain, liver and kidneys

This article discusses some of the nuances of blood supply to such important internal organs as the brain, liver and kidneys.

Brain blood flow

The general blood supply to the brain is relatively constant, and its intensity is quite high. As for local blood flow in different parts of the brain, it is determined by the intensity of their functioning. Thus, with the intense work of the brain, the local blood flow in its cortex can increase by two or three times in comparison with the intensity of blood flow at rest.

In the conditions of rigidity and tightness of the human skull, the overall resistance of the cerebral vessels to a small extent depends on changes in blood pressure. So, with increasing pressure in the arteries, they expand, which in turn increases the pressure of the CSF, its outflow into the spinal cavity and compression of the brain veins. At the same time, there is a decrease in arterial resistance and an increase in the resistance of veins. Thus, the resistance of the brain vessels, in general, practically does not change.

Myogenic influence on the blood supply of the brain is due to the reactions of smooth muscles of cerebral arterial vessels to changes in pressure in them. It refers to the central link of the autoregulatory system of cerebral circulation.

A powerful regulator of the blood flow of the brain is the level of tension in the arterial blood of carbon dioxide and the associated pH-level of the cerebrospinal fluid.

Metabolic effects on the blood supply to the brain are essential for local redistribution of blood flow between the brain regions, the functional activity of which in each individual situation has a different level. With a local increase in functional activity in nerve cells in the intercellular environment, the concentration of potassium and adenosine ions increases. This, in turn, leads to local vascular enlargement and increased blood flow in the vessels.

Neurogenic effects on the blood supply to the brain are considered less effective than metabolic regulation. The main zone of their application is the zone of arterial cerebral vessels, whose diameter is up to 25-30 microns. The main source of neurogenic influences on the blood supply to the brain are sympathetic postgonalonic fibers. In many ways, the nervous regulation depends on autoregulation, the stress of O2 and CO2, the initial vascular tone, concentration and composition of ions, as well as the presence of biologically active substances in the cerebrospinal fluid and brain tissues.

Blood supply to the liver

When entering the liver livers of the hepatic artery and vein, they are repeatedly divided into smaller vessels, accompanied along the entire bile ducts. The interlobular artery and interlobular vein with an interlobular duct are referred to the so-called "liver triad". Lymph nodes are located side by side. From around the lobular arteries and veins, the capillaries that go to the hepatic lobules and merge on their periphery, forming at the same time intra-lobular vessels. They flow mixed blood in the direction of the center of the lobule from the periphery and gather in the central vein, along which the blood flow from the lobule begins in the sublobular veins forming the main outgoing hepatic veins.

Blood supply to the kidney

The artery entering the gates of the organ branches into arteries, which, in turn, disintegrate into interlingual arteries. At the border of the cortical and cerebral matter, they pass into arteries, passing arched and parallel to the surface of the kidney. From these arteries, a large number of thin interlobular arteries, which are directed towards the surface of the organ, depart. Blood supply of the renal brain substance is carried out by direct arterioles, which depart from the arterial arteries. Short side branches from interlobular arteries enter the capsule of the glomerulus. In it, the branches turn into the capillary network. Then the arterial capillaries merge and the arterioles are removed.