When healthy, an abundant supply of qi (pronounced “chee”) or "life energy" flows through the body's meridians (a network of channels through the body). If the flow of qi in the meridians becomes blocked or there is an inadequate supply of qi, then the body fails to maintain harmony and order, and any number of symptoms can manifest. The disharmony of qi can result from environmental pathogens, stress, disease, or numerous lifestyle factors. Acupuncturists look carefully for these signs of health and dysfunction, assessing not only the presenting signs and symptoms, but also the medical history, general constitution, and other diagnostic tools such as pulse and tongue.