But these blood vessels are different from all the other blood vessels in our body. They are lined by a strange structure called the blood-brain barrier. It closely controls what is, and is not, allowed to leave the blood supply and enter the brain.It's your own personal customs and border security.We used to think of the blood-brain barrier as some kind of biological flyscreen.hey are lined by a strange structure called the blood-brain barrier. It closely controls what is, and is not, allowed to leave the blood supply and enter the brain. It's your own personal customs and border security. We used to think of the blood-brain barrier as some kind of biological flyscreen.
Follow this guide to find the best time to see Smoky Mountain fall colors. September. Fall in the Smokies begins in September, with the emerging changes occurring above 4,000 feet. Red, orange and yellow colors can be seen on sourwood, dogwood, maple, sassafras and birch trees. Drives recommended for September viewing are Parsons Branch Road, Newfound Gap Road and Clingmans Dome Road.
Plants in the Smokies. The Great Smoky Mountains National Park is part of the International Biosphere Project. It houses thousands of species of plants from mosses that only grow at the top of the mountains to trees that tower over the surrounding country side. It is easy to see why this area was made a national park, the beauty is only compounded by the flora in the mountains.