Cerebrospinal fluid


Cerebrospinal fluid is responsible for protecting the central nervous system by maintaining the fluid structures within it. This means that the entire central nervous system is essentially “floating” within the human body. This action not only protects, but lightens the central nervous system.


The brain of a human generally weighs 1500 grams. Within the human body, floating in the cerebrospinal fluid, the brain only weighs about 50 grams. The cerebrospinal fluid as it affects the brain creates a near neutral buoyancy. An object with neutral buoyancy does not float, nor does it sink. Additionally, the cerebrospinal fluid helps protect the brain from impact damage, creating a fluid cushion that disperses the impact.

During its travels through the central nervous system, the cerebrospinal fluid picks up waste product, just as the blood does in the circulatory system. The central nervous system is devoid of the option of lymphatic circulation and thus uses venous drainage for the removal of cellular wastes.


Cerebrospinal fluid is created through the unremitting process of filtration of the body’s blood plasma through clusters of highly specialized capillaries known as choroid plexuses as well as a smaller contribution from the secretions of the ependymal cells. Ependymal cells have cilia which cover the choroid plexus.

They are also part of the lining of the central canal and are thought to assist in the movement of the cerebrospinal fluid. To keep out the potentially dangerous fluids from the central nervous system, a blood cerebrospinal fluid barrier is created by the tight junctions of the ependymal cells.


Cerebrospinal fluid
Image: Cerebrospinal Fluid

The composition of the cerebrospinal fluid is very similar to that of blood plasma, in part because it originated from blood plasma. Just like the blood plasma it was formed from, the fluid contains white blood cells, proteins, urea, and glucose. The cerebrospinal fluid has higher levels of specific electrolytes, such as magnesium, sodium, chloride, and hydrogen.

It also contains lower levels of other electrolytes such as calcium and potassium. The body produces about 800 milliliters of cerebrospinal fluid every day. The most fluid the central nervous system can use at any given moment is 200 milliliters. The human body at rest in a horizontal state has a fluid pressure of 10 mmHg.
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