Chapter 5 Homework Acetycholine the disintegration of acetycholine is necessary to make repetitive nerve impulses to be effective and to allow for muscle repolarization PRIMARY TRANSMITTER OF THE PNS REGULATING MUSCLES o Controls voluntary movement of motor fibers of the spinal and cranial nerves and many involuntary muscles o Antibodies that interefere with the acetycholine action on muscle cells at neuromuscular junction affect movement as seen in myasthenia gravis o Deficient cholingeric projections in the hippocampus and orbitofrontal cortex have also been implicated in Alzheimer s disease Dopamine most important projections are the mesostriatal midbrain to striatum and mesocortical midbrain to cortex o degeneration of midbrain substantia nigra reduces the production and transmission of dopamine and is associated with Parkinson disease GABA gamma aminobutyric acid a major inhibitory neurotransmitter in the CNS implicated in hyperkinesia of Huntington chorea Glutamate main excitatory transmitter in the CNS used for fast neuronal transmission partially implicated in the brain damage secondary to stroke or degenerative diseases due to insufficient glutamate re uptake Neuronal pruning Axonal reaction retrograde degenerative changes occur un the cell body in response to sectioning the axon Wallerian degeneration the degenerative changes occur in the axon region detached from the cell body is the proximal segment and the detached axonal segment is the distal segment Multiple sclerosis autoimmune disease demyelination affects speed of nerve o Early symptoms are vision loss double vsion vertigo loss of balance conduction weakness numb limbs SHWANN CELLS PNS