Physiological Characteristics of the Heart
These may be summarized as the following two aspects.
1) Dominating Yang-qi
It is located in the upper-jiao, and belongs to a yang-viscus dominating yang-qi. As A Treatise on Blood Syndrome states: "The heart is a fire-viscus, it shines upon all things like the candlepower". This quotation indicates that yang-qi is quite strong and functions in not only warming the body, but also in propelling the blood circulation,thereby nourishing the whole body, and maintaining the activity of life. By virtue of the warming action of heart-yang, the decomposition, transportation, and transformation of the spleen and stomach, warming and evaporating functions of kidney-yang, and water metabolism of the entire body are all completed properly. Therefore, the ancients likened the heart to the "sun" in the celestial body.
2) Correspondence to Summer.
Man and the natural world are an integrated whole, and the five zang-viscera respectively correspond to the yin-yang of the four seasons. That the heart corresponds to summer is identical in meaning to the heart dominating yang-qi. The heart-yang is the most exuberant and vigorous during the summer months. If the heart is diseased, it is easier to enhance the patient's condition during the summer, for the heart is deriving added supplements from the natural environment.
Appendix: Pericardium
The pericardium, called" xinbao", is the outer membrane of the heart, it is the peripheral tissue surrounding the heart. Its meridian connects with the Triple-Jiao Meridian of Hand Shaoyang, and is both internally and externally related. In physiology, its main function is to protect the heart and promote the circulation of qi and blood in order to avoid injury. Because it has the ability to "order" the heart, it is known as the "heart dominating". It is believed in TCM that the evil invading the heart would first affect the pericardium. In the theory of warm-diseases, symptoms of mental derangement, such as coma and delirium appear. These are termed "the heat-evil invading pericardium", while the mental derangement due to phlegm-heat is termed "phlegm covering heart-orifice".
Both conditions are heart disorders. For this reason the pericardium is not generally considered an independent organ,but rather an attached organ of the heart.
