The Bloo1 - heroin readily enter the brain (because of...

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The Blood-Brain Barrier Cells in the brain require a very stable  environment to ensure controlled and  selective stimulation of neurons. As a  result, only certain materials are  allowed to pass from blood vessels to  the brain. Substances such as O 2 glucose, H 2 O, CO 2 , essential amino  acids, and most lipid-soluble  substances enter the brain readily.  Other substances, such as creatine and  urea (wastes transported in the blood),  most ions (Na + , K + , Cl ), proteins, and  certain toxins either have limited access 
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or are totally blocked from entering the  brain. Unfortunately, most antibiotic  drugs are equally blocked from  entering, while other substances such  as caffeine, alcohol, nicotine, and 
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Unformatted text preview: heroin readily enter the brain (because of their lipid solubility). This blood-brain barrier is established by the following: Brain capillaries are less permeable than other capillaries because of tight junctions between the endothelial cells in the capillary walls. The basal lamina (secreted by the endothelial cells) that surrounds the brain capillaries decreases capillary permeability. This layer is usually absent in capillaries found elsewhere. Processes from astrocytes (a type of neuroglial cell) cover brain capillaries and are believed to influence capillary permeability in some way....
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The Bloo1 - heroin readily enter the brain (because of...

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