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:
“I think “taste” is a social concept and not an artistic one. I’m willing to show good taste, if I can, in somebody else’s living room, but our reading life is too short for a writer to be in any way polite. Since his words enter into another’s brain in silence and intimacy, he should be as honest and explicit as we are with ourselves.”
—John Updike (b. 1932)
“What, girl, though grey
Do something mingle with our younger brown, yet ha’ we
A brain that nourishes our nerves, and can
Get goal for goal of youth.”
—William Shakespeare (1564–1616)
“The analogy between the mind and a computer fails for many reasons. The brain is constructed by principles that assure diversity and degeneracy. Unlike a computer, it has no replicative memory. It is historical and value driven. It forms categories by internal criteria and by constraints acting at many scales, not by means of a syntactically constructed program. The world with which the brain interacts is not unequivocally made up of classical categories.”
—Gerald M. Edelman (b. 1928)