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 dont know but a book in a mans brain is better off than a book bound in calfat any rate it is safer from criticism. And taking a book off the brain, is akin to the ticklish & dangerous business of taking an old painting off a panelyou have to scrape off the whole brain in order to get at it with due safety& even then, the painting may not be worth the trouble.”
—Herman Melville (18191891)
“If theyve a brain and cerebellum, too,
Theyve got to leave that brain outside,
And vote just as their leaders tell em to.”
—Sir William Schwenck Gilbert (18361911)
“She turns and looks a moment in the glass,
Hardly aware of her departed lover;
Her brain allows one half-formed thought to pass:
Well now thats done: and Im glad its over.”
—T.S. (Thomas Stearns)