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Nervous System
The nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and processes input from the senses and initiates actions. In animals with brains, the nervous system also generates and conducts thoughts and emotions. Thus it is the system that animates "animals" (sponges are an exception). Chemicals that target the activity of nerves generally are the most rapidly acting toxins, typically causing paralysis and/or death. Anatomy of the nervous systemThe nervous system consists basically of two types of cells:
Rapid signalling within the nervous system occurs by two primary mechanisms:
Vertebrate nervous systemsFor heuristic and other purposes, the nervous systems of vertebrate animals are often divided into a central (CNS) and a peripheral nervous systems (PNS). The CNS consists of the brain and spinal cord. The PNS consists of sensory pathways and motor pathways, the latter being divided into the somatic (voluntary) nervous system and the autonomic nervous system.The somatic nervous system is the voluntary part of the nervous where it coordinates the movement such as posture and walking. The autonomic nervous system is the involuntary part of the nervous system where all of the internal maintenance is taken care of. The autonomic nervous system is then divided into the sympathetic division and parasympathetic division. The sympathetic nervous system is responsible for the excitment that a person feels due to the increase of heartbeat. The parasympathetic nervous system, on the other hand, is the opposite of the sympathetic nervous system. This system is in play when a person is resting and feels relaxed due to the slowing down of the heartbeat.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Nervous System" and from Pain Busters Clinic
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