Phystut8b - MotorSystems December10 ,2009 MotorSystems...

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Motor Systems December 10 , 2009
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Motor Systems  Motor systems play an integral role in providing our body with the ability to undergo locomotion or movement. It is important that we have the coordination to hunt, eat, build shelters, and drink. Motor Systems provide this! It is through the highly coordinated function between the nervous system (PNS & CNS) with our muscular system which allows such movement.
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Overall Organization of the  Nervous system The overall organization of the nervous system is quite simple. Try to realize the various interactions and feedback systems between separate divisions. Today we will focus on how the nervous system and muscles interact to creative effective movement. Before a movement can be preformed, the CNS needs information on what muscles to move. 1. Which muscle it will move 2. The present length of the muscle it will move 3. The present tension of the muscle it will move. These three points are important!!
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The Motor Unit (Again)  Remember, the motor unit consists of, Alpha motor neuron All of the muscle fibers that it innervates Notice how one motor neuron branches near the end and innervates multiple muscle cells. (Large vs. Small motor units) The most basic difference is, Motor unit vs. Sensory Unit (efferent) (afferent)
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Somatic vs. Autonomic Motor  neurons Alpha Motor Neuron Ventral Horn Lateral Horn Note, the exit point out of the spinal cord. What neurotransmitters are released? Is every neuron myelinated? Alpha motor neurons only act on skeletal muscle (Ach only) And all are myelinated!
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Muscle Length and Tension  In order for the CNS to determine which muscles it must act, it first must receive some type of sensory input. What are the two primary types of sensory information that tell the CNS what muscles to move? Muscle Length Muscle Tension How does the brain get information about muscle length and muscle tension? Proprioceptors! The two main proprioceptors that we are concerned with in this course are the, Muscle Spindle and Golgi Tendon Organ.
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 Proprioceptors in Muscles Muscle Spindle Detects the length of a skeletal muscle and change in length . Runs parallel with the extrafusal (contractile) muscle fibers. Innervated by gamma motor neurons 1a afferents send information to the CNS about muscle length Golgi Tendon Organ It is in series with the tendon It tells the CNS information on muscle tension through 1b afferent fibers. It serves to protect muscles from damage by preventing overexertion of a muscle.
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The muscle spindle and golgi tendon organs are responsible for providing the CNS with information on muscle length and tension.
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This note was uploaded on 02/27/2010 for the course PHYSIOL 2210 taught by Professor Betts during the Spring '10 term at UWO.

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Phystut8b - MotorSystems December10 ,2009 MotorSystems...

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