Ch 2 > Five Zang Organs
 
           
 

The lung, situated in the thorax, communicates with the throat and opens into the nose. It occupies the uppermost position among the Zang-fu organs, and is known as the "canopy" of the Zang-fu organs. Its meridian connects with the large intestine, with which it is internally-externally related. Its main physiological functions are: dominating qi, controlling respiration, dominating dispersing and descending, dominating skin and hair, and regulating the water passages.

Dominating qi and controlling respiration

Dominating qi has two aspects: dominating the qi of respiration and dominating the qi of the whole body. Dominating the qi of respiration means that the lung is a respiratory organ through which the qi from the exterior and the qi from the interior are able to mingle. Via the lung, the human body inhales clear qi & exhales waste qi from the interior of the body. This is known as "getting rid of the stale and taking in the fresh".

The function of dominating the qi of the whole body means that the function of the lung in respiration greatly influences the functional activities of the whole body. It is closely related to the formation of pectoral qi, which is formed from the combination of the essential qi of water and food, and the clear qi inhaled by the lung. It accumulates in the chest, ascends to the throat to dominate respiration, and is distributed to the whole body in order to maintain the normal functions of the tissues and organs.

When the function of the lung in dominating qi is normal, the passage of qi will be unobstructed and respiration will be normal and smooth. Deficiency of lung qi may lead to general lassitude, feeble speech, weak respiration and shortness of breath.

Dominating dispersing, skin and hair

Dispersing here means, to distribute to the whole body, to warm and moisten the muscles, skin and hair. The skin and hair located on the surface of the body and including the sweat glands, serve as a protective screen to defend the body from exogenous pathogenic factors. The skin and hair are warmed and nourished by defensive qi and body fluid distributed by the lung, which controls respiration.
The pores of the skin also have the function of dispersing qi and regulating respiration. For this reason, Traditional Chinese medicine says: "the lung dominates skin and hair" and "the pores are the gate of qi".

The close physiological relationship between the lung, skin and hair means that they often affect each other pathologically. For example, exogenous pathogenic factors often invade the lung through the skin and hair, giving rise to symptoms such as aversion to cold, fever, nasal obstruction and cough, reflecting failure of the lung in dispersing.

If lung qi is deficient, failure of the lung in dispersing the qi of water and food can result in the skin becoming wan and sallow and lead to deficiency of the anti-pathogenic qi and hence, susceptibility to catching cold. When lung qi fails to protect the surface of the body, there may be frequent spontaneous respiration.

The lung dominates descending and regulates the water passage

As a general rule, the upper Zang-fu organs have the function of descending, and the lower Zang-fu organs the function of ascending. Since the lung is the uppermost zang organ, its qi descends to promote the circulation of qi and body fluid throughout the body and conduct them downwards.

Dysfunction of the lung, in descending, may lead to upward perversion of lung qi with symptoms such as cough and shortness of breath.

Regulating the water passages means to regulate the pathways for the circulation and excretion of water. The role of the lung in promoting and maintaining water metabolism depends on the descending function of lung qi. Dysfunction may result in dysuria, oliguria and edema.

Opening into the nose

The nose is the pathway for respiration. The respiratory and olfactory functions of the nose depend on lung qi. When lung qi is normal, the respiration will be free and the sense of smell accurate. Dysfunction of the
lung in dispersing, for example, due to invasion by wind-cold, will lead tonasal obstruction, runny nose, and anosmia(loss of smell). Excessive pathogenic heat in the lung will lead to shortness of breath and vibration of the ala nasi.

Since the throat is also a gateway of respiration and an organ of speech, through which the Lung Meridian passes, the flow of qi and the speech are directly affected by the state of the lung qi. When the lung is diseased, it usually causes pathological changes in the throat, such as hoarse voice and aphonia(loss of speech).

Note: The lung organs in TCM basically plays the same part as the respiratory system in western medicine, and are related to water metabolism, blood circulation and functions of the vegetative nervous system and the immune system.