sentences:  Although many hypotheses have been proposed, the anatomical and physiological basis for acupuncture points and meridians remains elusive.Hypotheses include neural signaling, with possible involvement of opioid peptides, glutamate, and adenosine, and correspondence to responsive parts in the central nervous system; or mechanical signaling, with involvement of connective tissue (fascia), and mechanical wave activation of the calcium ion channel to beta-endorphin secretion.In practice, acupuncture points are located by a combination of anatomical landmarks, palpation, and feedback from the patient.