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:
“Let every woman ask herself: “Why am I the slave of man? Why is my brain said not to be the equal of his brain? Why is my work not paid equally with his? Why must my body be controlled by my husband? Why may he take my labor in the household, giving me in exchange what he deems fit? Why may he take my children from me? Will them away while yet unborn?” Let every woman ask.”
—Voltairine Decleyre (1866–1912)
“When the situation is, what we would wish, nothing is so ill- timed as to hint at the circumstances which make it so: you thank Fortune ... you had reason—the heart knew it, and was satisfied; and who but an English philosopher would have sent notices of it to the brain to reverse the judgment?”
—Laurence Sterne (1713–1768)
“To accuse another of having weak kidneys, lungs, or heart, is not a crime; on the contrary, saying he has a weak brain is a crime. To be considered stupid and to be told so is more painful than being called gluttonous, mendacious, violent, lascivious, lazy, cowardly: every weakness, every vice, has found its defenders, its rhetoric, its ennoblement and exaltation, but stupidity hasn’t.”
—Primo Levi (1919–1987)