The human body is exposed to many diseases: viral, bacterial, fungal or mixed. To protect the body, nature created various barriers, because if not for them, then foreign microorganisms could easily get into our body. But what is a barrier?
Natural body barrier
By classical definition, a barrier is any structure that prevents penetration. For example, skin is also a barrier, and it has a protective function, at least from physical influence on it.
All of the above types of microorganisms can also penetrate the brain, causing such serious infectious diseases as syphilis of the brain, meningitis, encephalitis, and so on, and it is quite difficult to cure these infections. And the interesting question arises, why did the infection from the bloodstream enter the brain, but the medications that were administered did not. The answer is simple: all the patterns lie in the brain barrier, or more precisely, in the blood-brain barrier.
The blood-brain barrier: what is it?
The blood-brain barrier is a barrier between capillary blood and brain cells, which protects it from the penetration of foreign substances / microorganisms, which can cause damage.
It also performs the function of self-regulation of the composition of the nutrient medium in which brain cells live. Of course, this barrier does not protect the brain 100%. It depends on the length of stay of the substance in the blood, its concentration; external influences; body condition and so on.
What is the blood-brain barrier made of?
This is not an organ like a kidney, stomach or spleen. It cannot be seen on an ultrasound scan or felt through the anterior abdominal wall. The brain barrier is a combination of anatomical functions.
What does it consist of:
- Brain capillaries. The walls of the capillary have neither windows nor doors. Certain cells overlap each other, and the joints are covered with special plates. The spaces between the cells are quite small, so the movement of fluid from the capillary vessel into the tissue goes through its wall.
- The capillary wall alone is not enough. The second defense is located between the capillary and the brain cell. In this gap is a layer of neuroglia, consisting of a plexus of stellate cells of astrocytes and their processes of dendrites. Neuroglia change the oxidative potential of the incoming elements, on which the permeability of the brain barrier depends.
- The soft membranes of the brain and the vessels of the lateral ventricles also participate in the protection of the brain. The permeability of cerebral vessels is lower than that of capillaries, and the gaps between cells in the capillary wall are wider. Here the third stage of protection takes place.
In general, we found out what a barrier is, why it is needed and what it consists of.