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When there is damage to tissue, the related nerve cells begin what is called alpha sprouting, a proliferation of microscopic pain receptors that deal with excessive pain. The receptors are part of a protective survival mechanism. When the body is injured, the sympathetic nervous system activates neurohormones such as noradrenaline, which lock into the receptors to continue the feeling of pain. The pain in turn activates the system, telling it to protect itself, thus forming a feedback loop where pain repressors are secreted. Sometimes the pain is stronger than repression. The principle of alpha sprouting is crucial. When there is severe physical damage the system produces more alpha receptors or other types of pain receptors to handle the excess.

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