13.1 An Overview of the Nervous System

• NS subdivided into CNS and PNS. CNS is composed of brain and spinal cord. PNS has divisions, afferent division with somatic and visceral sensory nerves and efferent division with somatic and autonomic NS. Autonomic NS consists of parasympathetic and sympathetic divisions
• Nervous system consists of all nervous tissue in body
• NS anatomical subdivisions: central and peripheral
• Central nervous system (CNS) composed of brain + spinal cord
• CNS. Processes and coordinates sensory input and motor output
• CNS. Location of higher functions (intelligence, memory, learning, emotion)
• CNS. Development begins as mass of nervous tissue in tube
• CNS. Tube cavity decreases in size, thickness of walters and diameter become variety
• CNS. Narrow central cavity of developing spinal cord is central canal
• CNS. Expanded chambers of brain called ventricles, continuous with central canal
• CNS. Clear fluid called cerebrospinal fluid (CSF), fills central canal and ventricles and surrounds CNS
• Peripheral nervous system (PNS) consists of all peripheral nerves and nervous tissue outside CNS
• PNS. Provides sensory information to CNS
• PNS. Carries motor commands from CNS to peripheral tissues and systems
• PNS. Two divisions: afferent and efferent
• Afferent division of PNS carries sensory info to CNS
• PNS. Afferent division. Begins at receptors monitoring specific characteristics of environment
• PNS. Afferent division. Many receptors like sensory process, cell(s), organ(s)
• PNS. Afferent division. Stimulation of receptor carries info to CNS
• Efferent division of PNS carries motor commands from CNS to muscles/glands
• PNS. Efferent division. Begins in CNS and ends at an effector, a specialized cell for functions
• Both afferent and efferent have somatic and visceral components
• Afferent carries info from... Somatic sensory receptors monitor Sk muscles, joints, skin
• Afferent carries info from... Visceral sensory receptors monitor internal structures (Sm muscle, C muscle, glands, organs)
• Efferent consists of… Somatic nervous system (SNS) and autonomic nervous system (ANS)
• Somatic nervous system (SNS) controls Sk muscle contractions
• Autonomic nervous system (ANS), or visceral motor system, regulates Sm muscle, C muscle, glandular activity
• What are the two subdivisions of the nervous system?

  The central nervous system which is composed of the spinal cord and the brain. The peripheral nervous system which consists of all peripheral nerves and nervous tissue outside the CNS.
• What are the two subdivisions of the efferent division of the peripheral nervous system?

  Somatic nervous system which controls skeletal muscle contractions; and autonomic nervous system which regulates smooth muscle, cardiac muscle, and glandular activity.