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Nerves are large enough to have been recognized by the ancient Egyptians, Greeks, and Romans, but their internal structure was not understood until it became possible to examine them using a microscope.
"It is difficult to believe that until approximately year 1900 it was not known that neurons are the basic units of the brain (Santiago Ram? Equally surprising is the fact that the concept of chemical transmission in the brain was not known until around 1930 (Henry Hallett Dale) and (Otto Loewi).
There are, however, a few exceptions to this rule, notably including the part of the forebrain called the basal ganglia Arthropods, such as insects and crustaceans, have a nervous system made up of a series of ganglia, connected by a ventral nerve cord made up of two parallel connectives running along the length of the belly.
Typically, each body segment has one ganglion on each side, though some ganglia are fused to form the brain and other large ganglia.
A very important type of glial cell (oligodendrocytes in the central nervous system, and Schwann cells in the peripheral nervous system) generates layers of a fatty substance called myelin that wraps around axons and provides electrical insulation which allows them to transmit action potentials much more rapidly and efficiently.
Recent findings indicate that glial cells, such as microglia and astrocytes, serve as important resident immune cells within the central nervous system.
At first, they think it's Alison herself, but after her body is found, the girls realize that someone else is planning on ruining their perfect lives.
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Convicted of a decade old crime of transporting drug money to an ex-girlfriend, normally law abiding Piper Chapman is sentenced to a year and a half behind bars to face the reality of how life changing prison can really be.
Nerves that transmit signals from the brain are called motor or efferent nerves, while those nerves that transmit information from the body to the CNS are called sensory or afferent.
Most nerves serve both functions and are called mixed nerves.
Set in the fictional town of Rosewood, Pennsylvania, the series follows the lives of four girls, Aria Montgomery, Hanna Marin, Emily Fields, and Spencer Hastings, whose clique falls apart after the disappearance of their leader, Alison Di Laurentis.
One year later, the estranged friends are reunited as they begin receiving messages from a mysterious figure named "A", who threatens to expose their deepest secrets, including ones they thought only Alison knew.The vertebrate nervous system can also be divided into areas called grey matter ("gray matter" in American spelling) and white matter.