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)
“Shall quips and sentences and these paper bullets of the brain awe a man from the career of his humor? No, the world must be peopled.”
—William Shakespeare (1564–1616)
“Progress celebrates Pyrrhic victories over nature. Progress makes purses out of human skin. When people were traveling in mail coaches, the world got ahead better than it does now that salesmen fly through the air. What good is speed if the brain has oozed out on the way? How will the heirs of this age be taught the most basic motions that are necessary to activate the most complicated machines? Nature can rely on progress; it will avenge it for the outrage it has perpetrated on it.”
—Karl Kraus (1874–1936)