About functions of the heart, there are some similarities between traditional Chinese medicine and modern medical science.
In traditional Chinese medicine, the heart has two main physiological functions.
The first one is to control blood and vessels. The heart pushes blood to circulate and carry nutritive substances to every part of the whole body. The motivity of the heart is called “Qi” (氣) which is the smallest basic element of a body. The heart also can convert nutritive substances, Qi and body fluid into blood. The heart can control the dilating and constricting of vessels for keeping normal circulation of blood.
The second one is to keep mental activity. In fact, ancient Westerners also thought the heart controlled mental activity of a person. So in the English language, there are many phrases such as “at heart”, “by heart”, “broken heart”, “do one’s heart good”, “gain one’s heart” which are used to describe mental activity. In traditional Chinese medicine, keeping mental activity is related to the formation of blood. Blood nourishes mental activity. So if blood is deficient, mental activity will be affected badly such as insomnia and neuroses.
Because the heart controls blood and vessels, the status of the heart can be shown via the appearance of the face and the tongue. So a healthy person has a florid complexion and the color of his tongue is also florid. An anaemic patient has a pallid look and the color of his tongue is also pallid and a little thin. If vessels are not unimpeded, blood will be stagnated, and then the face will be a little bluish and purplish, and the tongue has not only such color but also petechiae. If the heart has “fire”, the face will be red, and the tongue even has small ulcers, and it results in excitability and irritability. If the heart can’t keep mental activity well, the tongue also can’t work well, and the person will be stammering, lisping or even aphasic.
The feeling of joy is related to the heart. If the Qi of the heart is ample, the heart can work well, and the person feels delighted and optimistic. But if the Qi of the heart is lacking, the person will have an emotional slump and feel languid.
The formation of sweat is also related to the heart. Body fluid is the source of sweat. Body fluid and blood nourish each other. So there is a word “Sweat and blood have the same source”. If blood is deficient, body fluid will be lacking, and then the formation of sweat will be reduced. If perspiring is in excess, body fluid will be seriously lost, and the blood of the heart will be much reduced too, so the heart will palpitate and the person will feel panicky. Conversely, if a person is excessively nervous or feels terrified, the heart won’t regulate normally the formation and excretion of sweat, and then the body will perspire very much.
According to the theory of traditional Chinese medicine, an important pathological cause of acute myocardial infarction is the sudden heavy loss of the heart’s Yang-Qi (陽氣), which functions are propelling and warming. So blood can’t be pushed by the heart, and the excretion of sweat loses control. The patient will be suffering from shock with a pallid face and lots of cold sweat.
In traditional Chinese medicine, the methods of treating mental diseases and neuroses are to regulate the functions of the heart. Though the truth is that the brain keeps mental activity, traditional methods of regulating the heart are still effective. It is said that, some foreign scientists found the character and temperament of a person who has a transplanted heart is not his past nature but the character and temperament of the original owner of the heart. So the functions of the heart are really mysterious.