The lungs are located in the chest, with one above and one below. Because the lungs are the largest, they are named ‘Hua盖’. Due to the tenderness of the alveoli and their intolerance to low temperatures, they are easily invaded by evil, hence also known as ‘Jiao藏’. They are the place of the spirit and the master of Qi, belonging to metal in the five elements. The key endocrine system of the lungs is: governing Qi, in charge of inspiration, governing the descent of the film propaganda, regulating the waterway, heading to the hundred meridians to govern the adjustment, in order to assist the heart in adjusting the operation of Qi and blood. The lungs are connected to the throat above, and the outer skin, connected to the nose, in the mind of worry, in the liquid of tears. The lung meridian of hand Taiyin and the small intestine meridian of hand Yangming interweave and belong to the lungs and intestines, so the lungs and intestines are externally related.

The key endocrine system of the lung

(1) Mastering Qi and governing inhalation The main function of the lung in mastering Qi includes: mastering the Qi in the whole body and the inhaling Qi. The lung is the master of Qi in the whole body, meaning that all the Qi in the body belongs to the lung and is governed by the lung. ‘Su Wen · Wu Xiang Sheng Cheng Pian’ says: ‘All Qi belongs to the lung’. Chen Xiuyuan in ‘Medical Real Easy’ says: ‘Qi passes through the lung, and the Qi of the five internal organs and six bowels meridians all belong to the lung Qi deficiency’. The lung is the master of Qi in the whole body, which is first reflected in the transformation of Qi, especially the transformation of Zong Qi, which mainly relies on the combination of the pure Qi inhaled by the lung and the primordial essence of the grains digested and absorbed by the intestines and stomach. Therefore, whether the lung’s inhalation function is perfect directly affects the transformation of Zong Qi and also affects the transformation of Qi in the whole body. Secondly, the lung is the master of Qi in the whole body, which also reflects on the buffering effect on the Qi circulation in the whole body. The respiratory movement of the lung is the movement of Qi rising and descending. The regular inhalation and exhalation of the lung plays a key buffering role in the rising and descending movement of Qi in the whole body.

The lung is the master of inhaling Qi. That is to say, the lung is the site of external gas exchange in the body. According to the lung’s inhalation, it inhales the pure Qi of nature and exhales the accumulated Qi in the body, completing the exchange of external gases. Through the continuous process of exhaling the turbid and inhaling the pure, destroying the old and establishing the new, it promotes the transformation of Qi, adjusts the movement of Qi rising and descending, and ensures the normal development of the body’s basic metabolism. ‘Su Wen · Yin Yang Ying Xiang Da Lun’ says: ‘The natural Qi is connected with the lung’. The lung is the master of Qi in the whole body and the inhaling Qi, which in fact all belong to the lung’s inhalation function. The uniform and moderate inhalation of the lung is the fundamental standard for the transformation of Qi and the smooth flow of Qi. Conversely, if the inhalation function is disordered, it must affect the transformation of Qi and the smooth movement of Zong Qi, and the function of the lung as the master of Qi in the whole body and the inhaling Qi will also weaken; if the lung loses its inhalation function, the pure Qi cannot be inhaled, the accumulated Qi cannot be expelled, and human life will come to an end. Therefore, the function of the lung as the master of Qi in the whole body lies in the lung’s inhalation function. However, the insufficient Qi and the abnormal movement of rising and descending, as well as the abnormal operation of blood and the metabolism of body fluids, can all affect the lung’s respiratory function and lead to abnormal inhalation.

(2) The main function of film publicity and descent can be simply explained as ‘publicity’, which is the publicity and distribution of film publicity, that is, the upward ascending and spreading of lung Qi. ‘Descent’ is to purify, clean, and reduce, that is, the downward passage and the function of maintaining the cleanliness of the respiratory system of lung Qi deficiency.

The lung is responsible for the physiological effects of film publicity, which is primarily reflected in three levels: First, according to the vaporization of the lung, it expels the accumulated Qi in the body. Second, it distributes the body fluids and grains transformed by the spleen accurately throughout the body, externally corresponding to the skin and hair, which is what is commonly said in ‘Ling Shu · Jue Qi’: ‘The upper焦 develops and designs, publicizes the flavors of the five grains, smokes the skin, fills the body, and moistens the hair, like dew and mist, which is called Qi’. Third, it adjusts the opening and closing of the defensive Qi of film publicity, transforms the body fluid after metabolism into sweat, and expels it outside the body. Therefore, if the lung fails to disperse, it can lead to poor breathing, chest tightness, shortness of breath, coughing, as well as nasal congestion, sneezing, and no sweating, and other pathological conditions.

The physiological function of the lung governing descent is mainly reflected in three aspects: first, inhaling the clear qi of nature; second, because the lung is the largest organ, as the covering organ, it distributes the clear qi inhaled by the lung and the body fluids and food grains transported to the lung by the spleen accurately downwards; third, it purifies the toxins in the lung and respiratory system and foreign matter, to maintain the cleanliness of the respiratory system. Therefore, if the lung fails to descend, it can lead to pathological conditions such as shortness of breath or superficial breathing, cough with phlegm, and hemoptysis.

The film propaganda and descent of the lung are opposite and complementary movements. In physiological conditions, they depend on and restrict each other; in pathological conditions, they often influence each other. Therefore, without normal film propaganda, there is no good descent; without good descent, it will inevitably affect normal film propaganda. When film propaganda and descent are normal, the airways are smooth, inhalation is even, and the external gas of the body can be exchanged normally. If the functions of the two lose harmony, it will lead to diseases such as ‘deficiency of lung qi in film propaganda’ or ‘deficiency of lung descent’, and symptoms such as asthma, cough, and lung qi ascending. Therefore, as stated in the ‘Question for the Simple’, ‘The lung is bitter for gas to ascend’, and in the ‘Great Discussion on the Truth of the Simple’, it is also said, ‘All qi is stuffy, and it belongs to the lung.’

(3) The communication and regulation of waterways refers to the communication; regulation, refers to adjustment; waterway, is the road for the operation and metabolism of dampness and moisture. The lung’s function of communicating and regulating waterways refers to the role of the lung’s film propaganda and descent in the distribution, operation, and metabolism of body moisture and dampness. The lung governs film propaganda, not only accurately propaganda body fluids and food grains to the whole body, but also governs the opening and closing of the body’s physiological functions, and adjusts the metabolism of sweat; the lung’s qi deficiency in descent not only brings the inhaled clear qi into the kidney, but also continuously transports the body’s dampness downwards, and turns it into urine, which is the source of urine. Through the vaporization function of the kidney and bladder, it is converted into urine and excreted outside the body. This is the function of the lung in adjusting the metabolism of dampness and moisture, which is also the endocrine system of the lung’s communication and regulation of waterways. Therefore, it is said that ‘the lung governs water flow’ and ‘the lung is the source of water’. If the lung’s function of communication and regulation of waterways is weakened, it can lead to the accumulation of dampness and phlegm, even swelling due to water overflow and other diseases.

(4) The gathering of the hundred vessels, the main governing of the season, refers to the meaning of gatherings and activities; the lung governing the hundred vessels means that all the blood in the body gathers and activities in the lung according to the meridians, and it carries out gas exchange based on the lung’s inhalation, and then distributes it throughout the body. As stated in the ‘Question for the Simple’, ‘When food qi enters the stomach, stagnated qi returns to the heart, indulges in the vessels, the qi flow passes, the meridian qi returns to the lung, the lung governs the hundred vessels, and focuses on the skin and fur.’