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:
“You are as still as a yardstick. You have a doll’s kiss.
The brain whirls in a fit. The brain is not evident.
I have gone to that same place without a germ or a stroke.
A little solo act that lady with the brain that broke.”
—Anne Sexton (1928–1974)
“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 that’s done: and I’m glad it’s over.””
—T.S. (Thomas Stearns)
““My mother is jelly-hearted and she has a brain of jelly:
Sweet, quiver-soft, irrelevant. Not essential.
Only a habit would cry if she should die....””
—Gwendolyn Brooks (b. 1917)