Background & Objective: Regulation of composition, volume and turnover of fluids surrounding
the brain and damp cells is vital. These fluids transport all substances required for cells and remove
the unwanted materials. This regulation tends to act as barrier to prevent free exchange of materials
between the brain and blood. There are specific mechanisms concerned with fluid secretion of the controlled
composition of the brain, and others responsible for reabsorption eventually to blood and the extracellular
fluid whatever their composition is. The current view assumes that choroidal plexuses secrete
the major part of Cerebrospinal Fluid (CSF), while the Blood-Brain Barrier (BBB) has a much less contribution
to fluid production, generating Interstitial Fluid (ISF) that drains to CSF. The skull is a rigid box;
thereby the sum of volumes occupied by the parenchyma with its ISF, related connective tissue, the vasculature,
the meninges and the CSF must be relatively constant according to the Monroe-Kellie dogma. This
constitutes a formidable challenge that normal organisms surpass daily. The ISF and CSF provide water and
solutes influx and efflux from cells to these targeted fluids in a quite precise way. Microvessels within the
parenchyma are sufficiently close to every cell where diffusion areas for solutes are tiny. Despite this,
CSF and ISF exhibit very similar compositions, but differ significantly from blood plasma. Many hydrophilic
substances are effectively prevented from the entry into the brain via blood, while others like neurotransmitters
are extremely hindered from getting out of the brain. Anatomical principle of the barrier
and routes of fluid transfer cannot explain the extraordinary accuracy of fluids and substances needed to
enter or leave the brain firmly. There is one aspect that has not been deeply analyzed, despite being
prevalent in all the above processes, it is considered a part of the CSF and ISF dynamics. This aspect is
the energy necessary to propel them properly in time, form, space, quantity and temporality.
Conclusion:
The recent hypothesis based on glucose and ATP as sources of energy presents numerous
contradictions and controversies. The discovery of the unsuspected intrinsic ability of melanin to dissociate
and reform water molecules, similar to the role of chlorophyll in plants, was confirmed in the
study of ISF and CSF biology.
Kinetics of a nucleoside release from lactide-caprolactone and lactide-glycolide polymers in vitro.
