Physiological Functions of the Heart
1) Dominating the Blood Vessels
The heart dominates both blood and blood vessels. The blood circulates within the vessels and is transported through the whole body, via the heartbeat. The blood vessels are the pathways through which blood circulates, and are often called "the residence of blood. "
The heart is the motive force organ for blood circulation, propelling the blood flow in an orderly fashion through the vessels thereby maintaining the normal physiological activities of all the viscera and tissues. In TCM, heart-qi is known as the substance which provides the normal heart's motive force and beating, as well as its blood circulation. Since the heart is linked with the blood vessels, the blood dominated by the heart is called heart-blood. It participates in blood circulation and nourishment of all internal organs and tissues. Heart-blood supplies the material energy, and simultaneously pours blood into the vessels of the heart itself so as to maintain all functional activities. Therefore only when the heart-qi is vigorous, the heart-blood ample, and the vessels smooth, can the function of dominating blood vessels remain normal. If the heart-qi and heart-blood are deficient,the motive force of promoting blood circulation can be weakened, resulting in various disorders. Stagnation of the heart-blood, obstruction of the blood vessels characterized by palpitation and stuffed chest sensations as well as stabbing pain in the precordial region may result from a deficiency. In addition, insufficiency of heart-blood may also lead to mental disorders. The qi pertains to yang and the blood to yin, according to the yin-yang theory. This is the reason for the terms "heart-yang", and" heart-yin", etc. The coordination of qi, blood, yin and yang of the heart maintains a relative equilibrium of the physiological body.
Whether or not the heart's function in dominating the blood vessels is normal, it may be examined objectively and is significant in guiding clinical practice. Heart-qi propels the circulation of blood within the vessels, and regular heartbeats force the blood vessels to rhythmically contract. The pulsation of an artery is referred to a "pulse" in TCM.Since the pulse is related to the heartbeat, its strength of strong or weak may indicate the functional states of the heart. For example, when heart-qi is vigorous, the blood ample and the heartbeat strong, the blood circulation will be smooth, with a rhythmic, even,and forceful pulse beat. The proper speed is a frequency of 4-5 beats per breath. Contrarily, an insufficiency of heart-qi and weak driving force may lead to the obstruction of the circulation of blood. This is characterized by an uneven, thin and weak pulse.
In addition, the heart dominating the blood vessels is also related to water
metabolism of the body, which manifests the promoting action to the circulation of water fluid. The heart pertains to yang-viscus, and vigorous yang-qi can warm and remove water-dampness, propel blood circulation, and promote water circulation. It plays the regulating role in water metabolism. Heart disease usually affects water metabolism and causes pathological changes of water metabolism disorder. For example, insufficiency of heartyang may lead to water metabolism obstruction, and excessive water-fluid remains inside the body. This is characterized by a stuffed sensation in the chest, abdominal distention, etc. Thus, the heart is one of the internal organs that regulate water metabolism.
2) Dominating the Mind
The heart dominates the mind is the same in meaning as "The heart houses the
mind". In traditional Chinese medical theory, the term "mind" is an abstract concept.
However in the broad sense, it refers to the outward activities of the life of the whole ody and is a high condensation of physiological activities. It means the vitality of the body,appearance, complexion, expression of the eye, speech, response, etc. , all of which are included in the scope of the mind. In the narrow sense of the phrase, it refers to such activities as spirit, consciousness and thinking, etc. Modern physiology holds that all these mental activities are attributable to the physiological function of the brain, which is a reflection of the brain to the external environment. However from a holistic viewpoint, traditional Chinese medicine believes that these mental activities are attributable to the physiological function of the internal organs respectively. Therefore, vitality is classified into
five aspects, which correspond to the five zang-viscera. Thus Chapter 23 in Plain Questions states: "The heart stores the mind," "The lung stores the soul," "The liver stores the etherial soul" "the spleen stores the intention," "The kidney stores the will". The spirit, consciousness and thinking activities of the human body are ascribed to the five zang-viscera, but more importantly, to the physiological functions of the heart. The heart is the residence of the mind, and is also the source of mental and emotional activities.
There also exists a close relationship between the physiological functions of both "the heart dominates the mind" and "the heart dominates the blood vessels". The reason for this is that the blood is the material base of mental and emotional activity. Only when qi and the blood of the heart are abundant and nourish the mind, can mental activities be normal, making individual alert, healthy consciousness, quick in thinking and responsive to the environment, and keeping a healthy balance in the external world. If the heart is diseased, the function of dominating the mind may be abnormal. There will be disorders of the spirit, consciousness and thinking activities. If qi and blood of the heart are insufficient, heart-spirit may be disquieted, and the manifestations will be insomnia, excessive dreaming, poor memory, restlessness. If blood-heat disturbs the heart-spirit, there will be restlessness, delirium, even coma, unconsciousness. If phlegm-fire disturbs heat-spirit, there will appear derangement of the mind, resulting in irritability, weeping and laughing without apparent reason, aggressive and violent behavior, etc.. From the above
description, it clearly shows that the heart disease may lead to abnormal manifestations of mental activity.
