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 could brain him with his lady’s fan.”
—William Shakespeare (1564–1616)
“One of the most singular facts about the unwritten history of this country is the consummate ability with which Southern influence, Southern ideas and Southern ideals, have from the very beginning even up to the present day, dictated to and domineered over the brain and sinew of this nation.”
—Anna Julia Cooper (1859–1964)
“We talk about a representative government; but what a monster of a government is that where the noblest faculties of the mind, and the whole heart, are not represented! A semihuman tiger or ox, stalking over the earth, with its heart taken out and the top of its brain shot away. Heroes have fought well on their stumps when their legs were shot off, but I never heard of any good done by such a government as that.”
—Henry David Thoreau (1817–1862)