Nervous System Anatomy and Physiology 1Functions of the Nervous SystemTo carry out its normal role, the nervous system has three overlapping functions.1.Monitoring changes.Much like a sentry, it uses its millions of sensory receptors to monitor changesoccurring both inside and outside the body; these changes are called stimuli, and the gatheredinformation is called sensory input.2.Interpretation of sensory input.It processes and interprets the sensory input and decides what shouldbe done at each moment, a process calledintegration.3.Effects responses.It then effects a response by activating muscles or glands (effectors) via motoroutput.4.Mental activity.The brain is the center of mental activity, including consciousness, thinking, andmemory.5.Homeostasis.This function depends on the ability of the nervous system to detect, interpret, andrespond to changes in the internal and external conditions. It can help stimulate or inhibit the activities ofother systems to help maintain a constant internal environment.Anatomy of the Nervous SystemThe nervous system does not work alone to regulate and maintain bodyhomeostasis; the endocrine system is asecond important regulating system.
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Nervous System Anatomy and Physiology 3Organization of the Nervous SystemWe only have one nervous system, but, because of its complexity, it is difficult to consider all of its parts at thesame time; so, to simplify its study, we divide it in terms of its structures (structural classification) or in terms ofits activities (functional classification).Structural ClassificationThe structural classification, which includes all of the nervous system organs, has two subdivisions- the centralnervous system and the peripheral nervous system.Central nervous system (CNS).The CNS consists of the brain andspinal cord, which occupy thedorsal body cavity and act as the integrating and command centers of the nervous systemPeripheral nervous system (PNS).The PNS, the part of the nervous system outside the CNS, consistsmainly of the nerves that extend from the brain andspinal cord.
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Nervous System Anatomy and Physiology 5Functional ClassificationThe functional classification scheme is concerned only with PNS structures.Sensory division. The sensory, or afferent division, consists of nerves (composed of nerve fibers) thatconvey impulses to the central nervous system from sensory receptors located in various parts of thebody.Somatic sensory fibers.Sensory fibers delivering impulses from the skin, skeletal muscles, and jointsare called somatic sensory fibers.Visceral sensory fibers.Those that transmit impulses from the visceral organs are called visceralsensory fibers.