Chinese people has its own medicine for more than 2000 years. It had stayed as a mainstream medicine until Western preachers and pilgrims bought Western medicine into China in the past 200 years. In contrast, Chinese people call its own medicine as Zhong Yi (中医), that is traditional Chinese medicine. The term traditional Chinese medicine had been a standard translation for Zhong Yi for many decades. All Zhong Yi universities in China were translated as traditional Chinese medicine university.
In the past decade, all universities simplified their English name as Chinese medicine university. Interestingly, the term traditional Chinese medicine remains by the regulatory body. So now, Chinese medicine has two meanings. One refers to traditional Chinese medicine (in contrast with Western medicine), the other means Chinese herbal medicine or Chinese herbs.
In its long history in China, Traditional Chinese medicine practitioners use herbs and acupuncture to fight all kinds of diseases. They wrote down their successful experiences and found answers why they could cure diseases in theories of Chinese philosophies. The whole medical system -- physiology, pathology, etiology, diagnosis, prevention and treatment, all are organized in the philosophical system. It is not unwise to say that traditional Chinese medicine is an outcome from therapeutic experiment directly on our human body instead on white rats, so its safety had been proved far before the establishment of Western medicine system.
There are three sets of ancient Chinese philosophies applied into traditional Chinese medicine. They are Qi (气), Yin Yang (阴阳), and Five Elements (五行). They categorize the natural world and our human being body into one, two and five respectively.
Everything is qi, everything is consists of qi, life comes from qi, life disappears in forms of qi. The environment in sky is called Tian Qi (sky qi), that in the woods or at beach or above desert are called Di Qi (earth qi); When one gets angary, his liver qi will gush out, when one won lottery, his heart qi will become pleasant; when water in a pot above a stove gets bubbling, qi (steam) would get its way out. Qi is a daily word in Chinese people's life.
The forms of qi is countless, but can be group into two, yin qi and yang qi, simplified as yin and yang. Yin Yang philosophers believe that life comes from the movement or interaction of Yin and Yang. Yin represents cooling, quiet, downward, soft, hiding, female, etc, while Yang refers to warming, noisy, upward, hard, showing, male, etc. Yin and Yang are opposite to each other and also relies on each other. The colorful life in this dynamic world comes from interaction of Yin and Yang.
This seems very abstract and hard to be understood, but take computer language as example, things would become very straight forward. The basic computer calculating unit is 1 and 0. Lining up these two symbols in different order and length, could create everything as our modern desk top can do.
Qi or yin qi and yang qi could fall into five categories, metal, mood, water, fire and earth. There are five types of personalities, five yin internal organs, five yang internal organs, five tastes, five kinds of fluid in the body, and five seasons, five colors, five body orifices, five special acupoints below elbows and knees, etc.
So these three sets of ancient Chinese wisdom are mixed to understand body structure and function, herb's properties, acupoints' relations, etc. In contrast with Western medicine which sits on modern science (chemistry, biology, physics, etc), traditional Chinese medicine, an empirical medicine, is submerged in Chinese ancient philosophies.
In traditional Chinese medicine "anatomy", the center of the body are the five zang (internal) organs. These five zang organs are the heart, lung, liver, spleen and kidney. They are superior to six fu organs (small intestine, large intestine, gall bladder, stomach, and urinary bladder) and governs five sense organs (tongue, nose, eyes, mouth, ears) respectively. These five zang organs also control five body parts (blood vessels, skin/pores, tendons/facias, muscles, bone) respectively.
The body has its essential substances to maintain its function. They are qi, blood, body fluid and essence. Five zang organs produce and store these substances. All body parts rely on these essentials. There are channels and collaterals conduct these materials away from five zang organs. The word "Zang" means hiding or staying in deeper part of the body.
Take several elements as example. In wood category in our body, there are liver, gall bladder, tendons, nails, eyes; in earth group, there are spleen, stomach, four limb muscles, lips, mouth; in fire category, there heart, small intestine, blood vessels, face, tongue. So in this way, five element theory binds the body parts from the internal to the external highly efficiently.
Traditional Chinese medicine gives its priority to etiology, or understand what causes a illness. There are various kinds of pathological factors in traditional Chinese medicine. They are external and internal factor causing different diseases. The external are six climatic factors (wind, cold, shu, heat, dryness, dampness). The internal are seven emotions (anger, joy, grief, worry, pensiveness, fear, fright). There are others: imbalance of diet, mental and physical activity, trauma, insect/animal bite, etc. These factors cause yin yang imbalance, qi and blood disorder, and dysfunction of internal organs.