Cerebrospinal fluid (CSF): composition and functions
It is popular knowledge that brain It is located inside the skull, being protected among other things by it and by different membranes, such as the meninges.
The correct functioning and protection of this organ is essential for survival, so it is necessary to nourish it and avoid possible damage, such as those produced by blows or intracranial pressure. In addition, in its necessarily continuous operation, residues are generated, which can be harmful and therefore must be removed from the system.
A very important liquid that circulates through the nervous system participates in all this, known as cerebrospinal fluid.
A general idea of cerebrospinal fluid
Cerebrospinal or cerebrospinal fluid is a substance present in the nervous system, both at the brain and spinal cord level, which performs various functions such as protection, maintenance of intracranial pressure and state of health of the thinking organ.
Its presence in the nervous system occurs especially in the subarachnoid space (between the arachnoid and the pia mater, two of the meninges that protect the brain) and the cerebral ventricles. It is a transparent liquid of fundamental importance in the conservation and
good brain health, with a composition similar to that of blood plasma, from which it is derived. Despite being colorless, different alterations and infections can give it different shades, its coloration being a sign of the presence of a problem.Cerebrospinal fluid life cycle
Cerebrospinal fluid is synthesized in the choroid plexuses, small structures present in the lateral ventricles, the main function of these plexuses being the production of this substance. This production occurs continuously, renewing itself to maintain a constant amount of said substance..
Once emitted, it flows from the lateral ventricles to the third ventricle and later to the fourth through the aqueduct of Silvio. From there it ends up projecting into the subarachnoid space through a hole known as the Magendie orifice and the Luschka orifices, openings located in the fourth cerebral ventricle that put the ventricular and meningeal systems in contact by communicating with the cisterna magna of the subarachnoid space (located between the arachnoid and pia mater). From that point on, it circulates through the meninges throughout the entire nervous system, performing various functions in the process.
To culminate its life cycle, it is finally reabsorbed through arachnoid granulations, which connect with the veins present in the dura mater, with which the liquid ends up reaching the torrent blood.
The average life cycle of this substance is around three hours, between its secretion, circulation, collection and renewal.
Composition
As just mentioned, the composition of cerebrospinal fluid is very similar to that of blood plasma, the main variations being the comparatively much lower presence of proteins (it is calculated that in the blood plasma the presence of proteins is two hundred times greater) and the type of electrolytes that are part of he.
A water-based solution, cerebrospinal fluid has several components of great importance for maintenance of the nervous system, such as vitamins (especially group B), electrolytes, leukocytes, amino acids, choline and acid nucleic.
Within this large number of elements, in cerebrospinal fluid the presence of albumin stands out as the main protein component, along with others such as prealbumin, alpha-2-macroglobulin or transferrin. Apart from these components, the high presence of glucose stands out, having about between 50 and 80% presence in this solution so vital for the brain.
Principal functions
We have visualized an overview of what cerebrospinal fluid is, where it circulates and what it is made of. However wonder why this substance is so important for the proper functioning of the entire nervous system. To answer this question it is necessary to see what functions it has.
One of the main functions of cerebrospinal fluid is to be the main mechanism of elimination of the residues produced by the continuous functioning of the nervous system, residues that could seriously affect its operation. Thus, the circulation of cerebrospinal fluid takes away those substances and metabolites, which will end up being excreted from the system. In the absence of this substance, the excess toxins and particles would become sedimented in regions of the nervous system and adjacent areas, so that many problems in the state of living cells: neither could they get rid of those excess elements, nor could they access the parts of these that can be recycled once they have passed through the site suitable.
Another of the most important functions of the cerebrospinal fluid is to keep the brain, as well as ensuring the constancy of the environment between the different cells of the brain and the marrow. It is a kind of chemical "buffer" that allows the room for maneuver to increase in the event of certain hormonal imbalances, for example, and when there are problems of homeostasis in general.
Cerebrospinal fluid also allows the brain to float within the skull, greatly reducing its weight. This flotation also serves as a cushion against aggressions, blows and movements by reducing the possibility of impact against the bones of the skull or external elements.
Also, cerebrospinal fluid has to do largely with the maintenance of intracranial pressure, making it neither too big nor too small, maintaining a constant balance that allows proper operation.
Finally, it also participates by acting as an immune system, protecting the nervous system from harmful agents. It also contributes as a means of hormone transport.
Derived disorders
Thus, the nervous system has in the cerebrospinal fluid an essential tool to function correctly.
However, It is possible that there are alterations in the synthesis, circulation or reabsorption of this substance, which can cause different problems, two of them being the following.
1. Hydrocephalus
This concept refers to the excessive presence of cerebrospinal fluid, having such accumulation that a pressure of the brain against the skull is caused. Some of the elements that can cause it are tumors, infections or trauma, but it is also common to find congenital hydrocephalus, that is, present from birth.
It can cause from headache, vomiting, cognitive or coordination impairment or double vision, among other symptoms, being in the case of congenital hydrocephalus reason for a strong difficulty in development and intellectual deficit. It is usually due to blockages in the circuit, a common example being the Magendie orifice becoming blocked. To treat these problems, it is possible to perform surgery in order to place an escape route for the liquid to other areas, such as the stomach.
2. Hypertension / Intracranial hypotension
An excess or deficit of cerebrospinal fluid can cause the pressure on the brain within the skull to be excessive or too low to allow proper function. While hypotension would occur due to the loss or low production of cerebrospinal fluid, hypertension would occur due to a excess of this, which can be serious because it puts pressure on areas of the nervous system and prevents them from working well (or even kills areas of tissue mobile).
In any case, the alterations in the cerebrospinal fluid that may appear in these cases add to the problems of the heart condition that causes, so that the danger increases. It is necessary to treat both groups of symptoms to avoid a chain effect resulting from problems in the functioning of the nervous system and the circulatory system.
Bibliographic references:
Rodríguez-Segade, S. (2006). Cerebrospinal fluid. Ed Cont Lab Clin.; 9: 49-56.
Rosenberg, G.A. (2008). Brain edema and disorders of cerebrospinal fluid circulation. In: Bradley, W.G.; Daroff, R.B.; Fenichel, G.M.; Jankovic, J. (eds). Bradley: Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann Elsevier; 63.
Zweckberger, K.; Sakowitz, O.W.; Unterberg, A.W. et al. (2009). Intracranial pressure-volume relationship. Physiology and pathophysiology Anaesthesist. 58:392-7.
