Myasthenia gravis is an illness in which antibodies attack the neuromuscular junction that connects muscles to nerves. The condition causes blockage of nerve impulses and subsequently muscles are weakened. Acetylcholine is a substance that transmits signals between muscles and nerves whereas acetylcholinesterase is a biological catalyst that results in destruction of acetylcholine. Acetylcholinesterase inhibitors treat the symptoms of myasthenia gravis by preventing destruction of acetylcholine by acetylcholinesterase.