Muscles and nerves are excitable tissues generating electrical signals when stimulated. When undisturbed or at rest, they are electrically silent. Barlas and colleagues1 investigated the electrical activity at trigger points, and they found two significant components: (1) intermittent high-amplitude spike potentials and (2) continuous, lower amplitude, noise-like recordings, which they called spontaneous electrical activity.
The author discovered similar electrical activity in response to peripheral pain in the neurons of the spinal cord and mid-brain (periaqueductal gray matter) in rats. In normal tissues, the neurons in the spinal cord and the periaqueductal gray matter are silent. When pain or inflammation is present in the muscles, the spikes and spontaneous electrical activity appear in both the spinal cord and the periaqueductal gray matter. As the pain intensity increases, the frequency of spikes increases and may reach more than 200 per second. Spike frequency in the nervous signaling system translates electro-physiologically into pain intensity.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.