Requirements of Motor Systems Sensory feedback from the involved muscles

Requirements of motor systems sensory feedback from

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Requirements of Motor Systems Sensory feedback from the involved muscles Continuously relayed to the cerebellum, basal ganglia, and sensory cortex Functioning neuromuscular junction that links nervous system activity with muscle contraction Movement Planning Premotor cortex generates a plan of movement Primary motor cortex is responsible for execution of a movement
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Motor Systems Pyramidal motor system Originates in the motor cortex Provides control of delicate muscle movement Extrapyramidal system Originates in the basal ganglia Provides background for the more crude, supportive movement patterns
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What Would You Call … A defect causing weakness in both arms? A weakness in the right arm and leg? Inability to move one leg? Inability to move both legs?
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Neurons Lower motor neuron lesions or infections; peripheral nerve injury Neuromuscular junction disorders Muscle atrophy or dystrophy Ach Motor endplate Dendrites receive stimuli; goes down axon Schwann cells make myelin (“white matter”) (PNS); helps increase AP conduction speed Motor unit - motoneuron and all of the fibers it innervates What Can Go Wrong With the Motor Unit?
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Synaptic Transmission What is happening at stages 1–3? What will result if you block stage 1? Stage 2? Stage 3?
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Organization of the Spinal Cord Dorsal Afferent Sensory Ventral Efferent Motor
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A Woman Developed Polyneuropathy … Her spinal nerves were damaged She lost the ability to tell where her body was positioned She has to look every time she takes a step, to tell where she is moving her feet to What parts of her spinal nerves were damaged? Dorsal or Ventral Nerves?
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Disorders of Skeletal Muscle Groups Muscular atrophy If a normally innervated muscle is not used for long periods, the muscle cells shrink in diameter, lose much of their contractile protein, and weaken Muscular dystrophy Genetic disorders that produce progressive deterioration of skeletal muscles because of mixed muscle cell hypertrophy, atrophy, and necrosis
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Alterations of Neuromuscular Function Drugs and agents can alter neuromuscular function by changing the release, inactivation, or receptor binding of acetylcholine Curare acts on the postjunctional membrane of the motor endplate to prevent the depolarizing effect of the neurotransmitter – blocks AchRs Used during many types of surgical procedures Clostridium botulinum blocks acetylcholine release and results in paralysis
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Neuromuscular Junction Problems Decreased acetylcholine release Botulism, caused by Clostridium botulinum Decreased acetylcholine effects on muscle cell Curare Myasthenia gravis Decreased acetylcholinesterase activity; acetylcholine has a stronger effect on the muscle cell Organophosphates
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Myasthenia Gravis Myasthenia Gravis is a disorder of transmission at the neuromuscular junction (NMJ) that affects communication
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  • Spring '15
  • Internal carotid artery, Anterior cerebral artery, Middle cerebral artery

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