The human body contains 95 to 100 billion neurons or nerve cells, according to Neurogenetics at the University of Tennessee Health Science Center. There are at least 85 billion of these cells in the brain alone, with estimates as high as 1 trillion.
While humans have approximately 100 billion nerve cells, some species, such as blue whales, have at least twice that number. The elephant’s brain is three times the size of a human’s and has three times the number of nerves, according to the University of Tennessee.
Nerves are split into three kinds, according to the University of Washington: sensory neurons, motor neurons, and interneurons. Motor neurons transmit information away from the central nervous system, whereas sensory neurons transmit information to the central nervous system. For example, information from the nose and ears, such as odours and noises, goes to the brain via sensory neurons. Sensory and motor neurons are linked via interneurons.
According to the University of Washington, nerve cells are quite similar to ordinary cells. They have a cell membrane and a nucleus that contains genetic material and organelles, as well as basic cellular functions. They do, however, differ from other cells in a number of ways. Dendrites and axons are the parts of nerve cells that transmit electrical signals to and from the central nervous system. Nerve cells are also not changed as frequently as other cells in the body. Although there is some evidence that new neurons can form in adults, the older a person grows, the fewer neurons he has.