What does Chinese medicine mean by entering the meridian and returning to the meridian?

Attribution, that is, attribution, refers to the attribution of drug action; Meridian, that is, the viscera and meridians of the human body. Meridian tropism is the direction of drug action. It is to closely link the action of drugs with the viscera and meridians of the human body, so as to illustrate the selectivity of drug action to a certain part of the body, thus providing basis for clinical syndrome differentiation and medication.

Entering meridian and entering meridian have the same meaning, such as entering lung meridian, which means that this medicine can be used to treat diseases of lung meridian. For example, the function of ginkgo biloba is to astringe the lung, stop asthma, stop turbidity and reduce stool. Used for excessive phlegm, asthma and cough, leukorrhagia, enuresis and frequent urination. Among them, astringing the lung and relieving asthma are used for excessive phlegm, asthma and cough, which is the embodiment of entering the lung meridian.