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Chapter 13 The Nervous System

Chapter 13 The Nervous System - Chapter 13 The Nervous...

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Chapter 13 The Nervous System: Neural Tissue  06/10/2007 12:49:00 1) Introduction: The nervous system controls and adjusts the activities of other systems. Relys on some form of chemical communication with targeted tissues and organs. The nervous system usually provides relatively swift but brief responses to stimuli by temporarily modifying the activites of other organ systems. 2) The Nervous System the nervous system has two anatomical subdivisions: the central nervous system and the peripheral nervous system. o The Central Nervous System (CNS) consists of the brain and spinal cord. Responsible for integrating, processing, and coordinating sensory input and motor output. Also the seat of higher functions: Intelligence, memory, learning, and emotion. The narrow central cavity that persists within the spinal cord is called the central canal; the ventricles are expanded chambers, continuous with the central canal, found in specific regions of the brain. Cerebrospinal fluid (CSF) fills the central canal and ventricles and surrounds the CNS. o The Peripheral Nervous System (PNS) includes all of the neural tissue outside the CNS. Provides sensory information to the CNS and carries motor commands from the CNS to peripheral tissue and systems. The PNS is subdived into two divisions: (both have somatic and visceral components) Afferent division= brings sensory information to the CNS. Begins at receptors that monitor specific characteristics of the environment. o A receptor may be a dendrite (a sensory process of a other cell specialized to perform specific functions. Efferent division= carries motor commands to muscles and glands. The afferent division carries information from somatic sensory receptors, which monitor skeletal muscles, joints, and the skin, and visceral sensory receptors, which monitor other internal tissues such as smooth muscle, cardiac muscle, and glands. The efferent division includes the somatic nervous system (SNS) , which controls skeletal muscle contractions, and the autonomic nervous system (ANS) , or visceral motor system , which regulates smooth muscle, cardiac muscle, and glandular activity.
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o The activities of the somatic nervous system may be voluntary or involuntary. Voluntary contractions are under conscious control. Raising arm muscles to bring full glass of water to lips. Involuntary contractions are directed outside of your awareness. Retracting hand from hot stove before feeling the pain. o The activities of the autonomic nervous system are usually outside our awareness or control. 3) Cellular Organization in Neural Tissue: Neural tissue contains two distinct cell types: nerve cells ( neurons ) and supporting cells ( neuroglia ).
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