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)
“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)
“So immense are the claims on a mother, physical claims on her bodily and brain vigor, and moral claims on her heart and thoughts, that she cannot ... meet them all and find any large margin beyond for other cares and work. She serves the community in the very best and highest way it is possible to do, by giving birth to healthy children, whose physical strength has not been defrauded, and to whose moral and mental nature she can give the whole of her thoughts.”
—Frances Power Cobbe (1822–1904)