Blood-brain barrier The blood contains many substances some needed for the brain whereas others limit it from playing its role. It is essential to restrict the entry of the unwanted materials by providing a neutral environment so as to ensure the brain can carry out its function. The blood brain barrier is responsible for regulating the substances in the blood that enters the brain and leaving others out. The paper will discuss the role of brain-blood barrier and how the structure helps it in its functioning. IntroductionThe central nervous system role in the body is to carry out neural signalling (Acker, 2014, p10).
The reliability of the brain in the discharge of neural signalling depends on the elements available in the system. The sensitivity is due to the functioning of the neurons that depend heavily on the composition of chemical and electric signals. It is important to maintain a neutral environment within the central nervous system, and the blood-brain barriers ensure such environment. The paper will discuss how the structure of the blood-brain barrier helps it in controlling the substances that enter the central nervous system from the brain and those that are left out.
The importance of the regulation will also be discussed as well as the entrance of drugs into the brain. Paul Ehrlich first noted the capability of the brain and spinal cord not being stained by dye injected into the blood in the year 1885 (Kliegman, 2016, p671). All the other body organs were stained leading him to conclude that the nervous tissues are incapable of absorbing the dye. Further development in the research was observed in 1913 when Edwin Goldmann, a student of Ehrlich injected dye into the cerebrospinal fluid (Kliegman, 2016, p672).
The results showed that the central nervous system was stained leading to the conclusion that there is a permeable barrier between the brain and cerebral spinal fluid and an impermeable barrier between the central nervous system and the blood. Structure of blood brain barrier The endothelial cells of the blood-brain barrier are different those of other parts of the body in several ways helping the structural composition in playing its function.
The blood-brain barrier endothelial cells contain both tight junctions and adherens junctions. The tight junctions regulate the polar solutes and the macromolecules contained in the blood plasma from dissolving into the brain extracellular fluid through diffusion (Kliegman, 2016, p673). The number and the distribution of tight junctions vary across the endothelial cells. They contain Claudin and Occludin proteins that are widely spread across the intercellular cleft (Neuwelt, 2013, p132). The arrangement of these proteins is equally essential to the functioning of the tight junctions as is their presence. Claudin 1 and 2 are the main types of Claudin protein found in the tight strands.
Researchers have identified more than twenty types of protein. The type of Claudin contained in blood brain barrier is Claudin 1 and 5 (Neuwelt, 2013, p 133). Although Claudin is the main component of tight junctions, concentration of Occludin in the central neural system is higher as compared to that of non-neural tissues (Acker, 2014, p28). Occludin is a critical component of the brain endothelial cells as it modulates paracellular permeability. The structure of Occludin helps tights junctions in carrying out their regulating functions.
The Occludin and Claudin strand are known to contain mediums that are flexible allowing the tight junctions to diffuse ions and hydrophilic molecules. Another protein found in the tight junctions is the junction adhesion molecule.