Week 6 & Week 7 - Nervous System Neurons Functional...

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Nervous System 20/02/2008 14:04:00 Neurons Functional units of the nervous system. The Nervous System     Integrates and coordinates many of the body’s activities Two primary divisions o Central Nervous System (CNS)     Brain and spinal cord o Peripheral Nervous System (PNS)     All nervous tissue outside the CNS Cells of the Nervous System     Neuroglial cells o Glial cells o More numerous o Do not participate directly in the transmission of electrical signals o Provide support for neurons Neurons o Functional units of the nervous system
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o Three general types of neurons o Neuron structure Three Types of Neurons Sensory neurons (afferent) Interneurons Motor neurons (efferent) Sensory Neurons Afferent neurons Carry information toward the CNS from sensory receptors Interneurons     Association neurons Between sensory and motor neurons In brain and spinal cord Integrate/interpret sensory signals and decide on appropriate response Most numerous in body (99%) Motor Neurons     Efferent neurons
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Carry information away from the CNS to an effector o Muscle or gland o Generate response Neuron Structure     Neurons are uniquely shaped with long processes that extend outward from  the cell body Three parts necessary for function in communication: o Cell Body “Control center” of neuron Nucleus and other organelles found here o Dendrites Thin, branched processes Carry information toward the cell body of a neuron “Receiving” portion o Axon Long extension that branches near end into axon terminals Carries information away from the cell body “Sending” portion Question: Which of the following best traces the flow of information through a  “typical” neuron?
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Answer: Dendrite -> Cell Body -> Axon Question: Which type of glial cells are responsible for forming myelin sheath in  PNS? Answer: Schwann Cells Myelin Sheath     Structure: o Insulating outer layer around axons o Composed of the plasma membrane of Schwaan cells that wrap  around axon o Gaps between Schwann cells on an axon called Nodes of Ranvier Function: o Speeds up conduction of electrical signal sown axon o Helps in repair of damaged neurons Multiple Sclerosis     Results from the destruction of the myelin sheath that surrounds axons found  in the CNS Nerves     Bundles of parallel axons from many neurons Covered with tough connective tissue
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Three types of nerves o Sensory nerves      – Contain sensory neurons o Motor nerves      – Contain motor neurons o Mixed nerves  
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This note was uploaded on 04/22/2009 for the course BIO 309D taught by Professor Jessicawandelt during the Spring '08 term at University of Texas at Austin.

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Week 6 & Week 7 - Nervous System Neurons Functional...

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