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, 書式設定, 書式設定,第 2 ,第 3 ,第 4 ,第 5 ,*, 書式設定, 書式設定,第 2 ,第 3 ,第 4 ,第 5 ,*,blood-brain barrier (BBB),Hua fu,Q:279486524,1,Key functions of the BBB,Discovery of the blood-brain barrier,Anatomy of the blood-brain barrier,Circumventricular organs,Factors that can lower the blood-brain barrier,B,lood-brain border,and,Glucose,Blood-brain barrier permeability in the mouse brain,Outline,2,Key functions of the BBB,A mechanism that controls the passage of substances from the,blood,into the,cerobrospinal fluid,and thus into the,brain,and,spinal cord,. The blood-brain barrier (BBB) lets essential metabolites, such as,oxygen,and,glucose, pass from the blood to the brain and,central nervous system,(CNS) but blocks most molecules that are more massive than about 500 daltons. This is a low mass in biomolecular terms and means that everything from,hormones,and,neurotransmitters,to,viruses,and,bacteria,are refused access to the brain by the BBB. It also means that many drugs, which would otherwise be capable of treating disorders of the CNS, are denied access to the very regions where they would be affective.,3,Key functions of the BBB are:,Protecting the brain from foreign substances (such as,viruses,and,bacteria,) in the blood that could injure the brain,Shielding the brain from hormones and neurotransmitters in the rest of the body,Maintaining a constant environment (,homeostasis,) for the brain,4,Discovery of the blood-brain barrier,The special properties of the blood-brain barrier were first observed in the late 19th century by the German bacteriologist Paul,Ehrlich,. He found that when he injected colored dyes into the blood stream they leaked out of,capillaries,in most regions of the body to stain the surrounding tissues; the brain, however, remained unstained. Ehrlich wrongly surmised that the brain had a low affinity for the dyes. It was his student, Edwin Goldman, who did the other half of the experiment and realized the truth of what was going on. Goldman injected a dye into the,cerebrospinal fluid,that surrounds the brain and observed that it stained the brain, but nothing else. Goldmann correctly concluded that the dye was unable to cross the specialized walls of brain capillaries.,5,Anatomy of the blood-brain barrier,Diagram of the blood-brain barrier transverse to a capillary,6,(A) Diagram of a brain capillary in cross section and reconstructed views, showing endothelial tight junctions and the investment of the capillary by astrocytic end feet. (B) Electron micrograph of boxed area in (A), showing the appearance of tight junctions between neighboring endothelial cells (arrows). (A after Goldstein, Goldstein and Betz, 1986; B from Peters et al., 1991.),Anatomy of the blood-brain barrier,7,8,Circumventricular organs,The circumventricular organs are regions of the brain where the blood-barrier barrier is weak. These regions allows substances to cross into brain tissue more freely and thereby allow the brain to monitor the makeup of the blood.,9,Various factors and conditions can lead to a lowering of the BBB. These include:,Hypertension (,high blood pressure,),Hyperosmolitity (a high concentration of a substance in the blood),Microwaves,Radiation,Infection Injury to the brain due to trauma, ischemia,inflammation, or pressure Additionally, the BBB is not fully formed at birth.,Factors that can lower the blood-brain barrier,10,B,lood-brain border,and,Glucose,To metabolize glucose in the brain, or to perform cerebral glucose metabolism, requires a complex, multi-step process in which the sugar is transported into the brain-breaking the well walled blood-brain border, converted to another substance, completes a set of chemical reactions, and then ultimately oxidized to carbon dioxide and water for the full use of it as energy.,Blood-brain barrier,11,Blood-brain barrier permeability in the mouse brain,Masaki Ueno.,Acta Neuropathol (2004) 107 : 532538,12,Blood-brain barrier permeability in the,rat,brain,Fig. 2AF,Light microscopic photographs showing the staining for HRP with TMB in WKY (,A,and,D,), SHR (,B,and,E,), and SHRSP (,C,and,F,).,D,E,and,F,are higher-power magnifications of,the staining for HRP with TMB in the hippocampal area indicated by,arrows,in,A,B, and,C, respectively. No HRP staining is observed in the hippocampus and cortex of WKY (,A,and,D,). The staining for HRP is seen in the hippocampus, especially around vessels (,E, F,:,arrows,) along the hippocampal fissure of SHR,(,B,and,E,) and SHRSP (,C,and,F,). Scale bars indicate 1mm,Masaki Ueno.,Acta Neuropathol (2004) 107 : 532538,13,Nicolas,.American Journal of Hypertension, 2010,14,Thank a lot !,15,
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