According to traditional Eastern medicine, each of the Five Elements has its own Yin aspects and Yang aspects. In our bodies, the Yin aspects of the Five Elements are embodied in five Yin organs, which are the liver, heart, spleen, lungs and kidneys. As for the Yang aspects of the Five Elements, they are embodied in six Yang organs, which are the gall bladder, small intestine, stomach, large intestine, urinary bladder, and San Jiao (or Samcho in Korean).
According to traditional Eastern medicine, the five Yin organs are largely responsible for our bodily functions. Yin organs are situated deeper inside the body, manufacturing, regulating, and conserving vital substances. They are more closely related to the Five Elements and thus more susceptible to the imbalance of a particular element that is assigned to them. Conversely, problems in any of these organs could offset the general imbalance of an element associated with the organ.
Heart – Yin organ of Fire
The heart is the Yin organ of the Fire Element. A healthy heart makes us vigorous, energetic, lively, and affectionate, all of which are associated with the Fire Element. A healthy heart also enables us to freely express and experience joy, the emotion of Fire. Given that the heart is closely interlaced with the emotion of joy, joy keeps our hearts healthy when it is appropriately felt and expressed. However, excessive joy is harmful to the heart.
In our bodies, the heart performs extremely important functions in maintaining our lives. The heart constantly pumps blood into every part of the body, governing the blood and blood vessels, both of which are assigned to the Fire Element. The heart also regulates our mental activities, generating thoughts and perceptions, according to traditional Eastern medicine. In fact, a cause for a certain mental disorder could be found in the heart. For example, an unhealthy heart could provoke forgetfulness and a cluttered thought process. Excessive heat in the heart, in particular, could provoke schizophrenia, according to Eastern medicine.
The fact that the heart controls our mental activities may raise quizzical eyebrows from many people who acknowledge the brain as the house of thoughts. However, Shen (or Shin in Korean), which could be understood as the spirit or the mind, resides in the heart, not in the brain, according to Eastern medicine.
As mentioned in Taoist sexology: Is sex good or bad? Shen is one of the three treasures of the human body. It is our Shen that connects us to spirituality and divinity. When our Shen is balanced, our thoughts are clear and coherent; we could have a deep and sound sleep at night; and we are motivated by a secure sense of purpose in life.
To the contrary, an unhealthy Shen leads to an unhealthy mental and emotional state. For example, our thoughts could be befuddled; we could be subject to insomnia; and in extreme instances, we could be mentally deranged, according to traditional Eastern medicine. Given that the heart is where Shen resides, the health of the heart is important for our mental and emotional well-being.
The heart also controls the tongue, the sensory organ of the Fire Element. Therefore, it is possible to diagnose the conditions of the heart based on the conditions of the tongue. For example, a pale tongue could indicate weak Qi energy in the heart and poor blood circulation. A decomposed tongue could suggest blood coagulations in the heart. Unusual redness at the tip of the tongue could indicate excessive heat in the blood. A purple color in the tongue could reveal the stagnation of the blood in the heart, according to traditional Eastern medicine.
Small intestine – Yang organ of Fire
The small intestine is the Yang organ of the Fire Element and is connected to the heart via meridians. The role of the small intestine in traditional Eastern medicine is not much different from what modern medicine acknowledges. The organ receives food and water from the stomach and transforms them to useful energy. It also separates the impure from the pure. It processes the pure and transmits it to the spleen. The small intestine sends the impure to the large intestine or to the bladder, so that the impure can be excreted.