Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few invertebrates such as sponges, jellyfish, adult sea squirts and starfish do not have one, even if diffuse neural tissue is present. It is located in the head, usually close to the primary sensory organs for such senses as vision, hearing, balance, taste, and smell. The brain of a vertebrate is the most complex organ of its body. In a typical human the cerebral cortex (the largest part) is estimated to contain 15–33 billion neurons, each connected by synapses to several thousand other neurons. These neurons communicate with one another by means of long protoplasmic fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.
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Famous quotes containing the word brain:
“To me the sole hope of human salvation lies in teaching Man to regard himself as an experiment in the realization of God, to regard his hands as God’s hand, his brain as God’s brain, his purpose as God’s purpose. He must regard God as a helpless Longing, which longed him into existence by its desperate need for an executive organ.”
—George Bernard Shaw (1856–1950)
“who chained themselves to subways for the endless ride from Battery
to holy Bronx on benzedrine until the noise of wheels and children
brought them down shuddering mouth-wracked and battered bleak of brain and drained of brilliance in the drear light of Zoo,”
—Allen Ginsberg (b. 1926)