A 34-year-old woman

presents with complaints of progressive weakness. She says that her symptoms get

worse toward the end of the day, she has difficulty swallowing and smiling, and

she sometimes gets double vision. She is diagnosed with myasthenia gravis, an

autoimmune disorder in which muscle cells cannot respond appropriately to

neural stimulation. Autoantibodies bind to and destroy acetylcholine receptors

on the postsynaptic membrane of the muscle fiber. What does this disease in

muscle fibers lead to?