Sistema Nervioso

Nervous system:
Is a group of organization that receives processes and transmit electrical signals. The vertebral nervous system, including that of humans, can be divided in two parts: central andperipheral. Each of these has further subdivisions. The central nervous system consists of a brain, and a spinal cord. The peripheral nervous system consists of neurons that lie outside of the CNS and9 axons that connect these neurons with the CNS.
The principal function of nervous system is to control psychological processes in conjunction with the endocrine system, senses the environment anddirects behavior. Other principal function is to receive electrical signals, send it to the brain which transforms it in answer and send it to the body for the environment.
The nervous system derivesits name from nerves, which are cylindrical bundles of fibers that emanate from the brain and central cord, and branch repeatedly to innervate every part of the body. Nerves are large enough to havebeen recognized by the ancient Egyptians, Greeks, and Romans, but their internal structure was not understood until it became possible to examine them using a microscope. A microscopic examinationshows that nerves consist primarily of the axons of neurons, along with a variety of membranes that wrap around them and segregate them into fascicles. The neurons that give rise to nerves do not lieentirely within the nerves themselves—their cell bodies reside within the brain, central cord, or peripheral ganglia.
All animals more advanced than sponges have nervous systems. However, even sponges,unicellular animals, and non-animals such as slime molds have cell-to-cell signalling mechanisms that are precursors to those of neurons. In radially symmetric animals such as the jellyfish and hydra,the nervous system consists of a diffuse network of isolated cells. In bilaterian animals, which make up the great majority of existing species, the nervous system has a common structure that...