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)
“If they’ve a brain and cerebellum, too,
They’ve got to leave that brain outside,
And vote just as their leaders tell ‘em to.”
—Sir William Schwenck Gilbert (1836–1911)
“The true charm of pedestrianism does not lie in the walking, or in the scenery, but in the talking. The walking is good to time the movement of the tongue by, and to keep the blood and the brain stirred up and active; the scenery and the woodsy smells are good to bear in upon a man an unconscious and unobtrusive charm and solace to eye and soul and sense; but the supreme pleasure comes from the talk.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)