体液受冷凝滞或遇热煎熬，都会使体液的黏度增加，这就是痰。这种痰，已不是

体液受冷凝滞或遇热煎熬，都会使体液的黏度增加，这就是痰。这种痰，已不是人体正常的体液，因为浓度高，无法与细胞内物质发生交换，甚至阻碍正常细胞代谢。这是变质的体液，残留在体内，而且是流动的，粘浊的，会诱发人体很多的不适症，产生很多的症状。

Cold stagnation or heat suffering of body fluid will increase the viscosity of body fluid, which is phlegm. This kind of phlegm is no longer the normal body fluid of human body. Because of its high concentration, it can not exchange with intracellular substances, and even hinder normal cell metabolism. This is a deteriorated body fluid, which remains in the body, and is flowing and muddy. It will induce a lot of discomfort and produce a lot of symptoms.

The viscosity of body fluid will increase if it is stagnated by cold or suffering from heat, which is phlegm. This kind of sputum is no longer a normal body fluid, because of its high concentration, it can't be exchanged with intracellular substances, and even hinders normal cell metabolism. This is a deteriorated body fluid, which remains in the body, and it is fluid and sticky, which will induce many discomfort and symptoms.