Heart houses the mind and stores the spirit (Shen). The ancient text Spiritual Axis states, "The heart is the Monarch of the five yin organs and the six yang organs and it is the residence of the Mind¡­." It is said that the brain controls intelligence and memory, but it is the heart that reflects the inner consciousness, emotions, and the spiritual aspects of a human being. If one's heart functions normally, then there will be healthy consciousness and sound mental activities. On the other hand, if the heart is diseased, there is a tendency for the Mind not to be rooted and the Shen or spirit is disturbed; then there will be mental restlessness, depression, anxiety, and insomnia and/or disturbed sleep and excessive dreaming.

There is a Chinese phrase known as Jing Shen which I use quite often when teaching at colleges. It is translated as vitality (Jing) and spirit (Shen). I have joked in the classroom that a student with good Jing Shen is alert, energetic, and enthusiastic and has a bright complexion and a twinkle in his/her eyes. This student has the heart for learning.

Heart is related to joy in human emotion. Joy or happiness is beneficial to the heart and improves blood flow. Joy makes the heart qi harmonize, leading to the proper nourishment by the blood to the heart muscles. But if a person is overjoyed, manic, or overly excited, the heart is excessively stimulated. This type of damage to the heart due to an impairment of heart spirit is seen with addicts who take recreational drugs. Similarly, overexcitement can trigger chest pains in a heart attack victim.

Heart meridian and channel system. A text on acupuncture used at the Shanghai College of Traditional Chinese Medicine states that the heart "channel begins in its associated organ, the heart, then emerges through the blood vessel system surrounding the heart, and travels downward across the diaphragm where it connects with the small intestine. A branch of the channel separates the heart and ascends alongside the esophagus to the face where it joins the tissues surrounding the eye. Another branch goes directly from the heart to the lung, then slants downward to emerge below the axilla. From here, the channel descends along the medial border of the anterior aspect of the upper arm, behind the lung and pericardium channels, to the antecubital fossa, where it continues downward to the capitate bone proximal to the palm. It then enters the palm and follows the medial side of the little finger to the finger tip."

The heart meridian is directly joined to the lungs, small intestine, and kidneys. An example of pathology of heart and lung is congestive heart failure (CHF). The lungs, according to TCM, are responsible not only for respiration but also for dispersing and descending water and other functions of water/fluid metabolism. In CHF, there is inadequate pumping of the heart due to fluid buildup in the lungs and edema in other tissues. Examples of pathology of the heart and small intestine are intestinal and urinary disorders that can arise from a stressful heart.

The TCM concept is that the kidneys are the basic constitution or gate of vitality and the motivating force of all functional activities of the internal organs. When the kidney is weak due to overwork, late nights, inadequate sleep, excessive drug use, frequent pregnancy, febrile illness, bad diet, etc, it cannot support the heart yin. Because of the imbalance, the yin of the kidney is not able to nourish the heart, causing the heart to be stressed and agitated (heart fire). This leads to added pressure to the systemic arterial blood circuit, as in the case of hypertension.