The Six Fu Organs and the Extraordinary Fu Organs
The Six Fu organs refer to the six organs: the gallbladder (Dan), stomach (Wei), large intestine (Da Chang), small intestine (Xiao Chang), bladder (Pang Guang), and the San Jiao (Triple Burner). In ancient times, “Fu” was synonymous with “Fu” (storehouse), meaning a hollow place for storing items, allowing for both intake and output. The Six Fu organs are mostly hollow visceral organs, and their common physiological function is to receive, store, and transform food and fluids. The common physiological characteristic of the Six Fu organs is “to drain but not to store,” functioning in a descending manner and facilitating movement. The Six Fu organs are interconnected and work closely together to complete the entire process of digestion, absorption, and excretion of food.
The Extraordinary Fu organs include the brain (Nao), marrow (Sui), bones (Gu), vessels (Mai), gallbladder (Dan), and uterus (Zi Gong). The term “Extraordinary” means “unusual,” and “Fu” means “constant,” as they share similarities with the Fu organs in form and function, hence their uniqueness. Among them, the gallbladder is one of the Six Fu organs and also belongs to the Extraordinary Fu organs. This section mainly discusses the physiological functions and characteristics of the Six Fu organs, brain, and uterus.
1.The gallbladder governs the storage and excretion of bile
The gallbladder is located within the right hypochondrium, attached to the liver’s small lobe, and is connected to the liver. Its shape resembles a pouch, hence it is referred to as the “gallbladder”. The gallbladder stores bile, which is transformed from the essence of the liver’s qi; in ancient times, bile was referred to as “essence juice” or “clear juice,” thus the gallbladder is also called the “storehouse of essence” or “storehouse of clarity”.
1. The gallbladder governs the storage and excretion of bile
Bile is yellow-green and extremely bitter. The formation and secretion of bile come from the liver, as it is “derived from the excess qi of the liver, overflowing into the gallbladder, and accumulating therein.” Therefore, the secretion and excretion of bile are an important aspect of the liver’s dispersing function. After bile is generated, it flows into the gallbladder for storage. After eating, through the liver’s dispersing action, bile is released into the intestines, assisting the spleen and stomach in maintaining normal digestion. Since the liver and gallbladder are closely related through the meridians, when the liver’s dispersing function is normal, the qi mechanism is smooth, and bile can be successfully released into the digestive tract to aid digestion. If the liver is diseased, it will affect bile production, leading to abnormal excretion and digestive dysfunction. For example, if the liver and gallbladder fail to disperse properly, bile may overflow into the skin, causing jaundice; if gallbladder qi reverses, bile may rise, leading to a bitter mouth; if bile excretion is obstructed, it may result in symptoms such as loss of appetite, abdominal distension, and loose stools. Gallbladder disease can also affect the stomach, causing nausea and vomiting; if bile stagnates, it may transform into heat, and damp-heat accumulation can further congeal bile, forming stones.
2. The gallbladder governs decision-making
As stated in the “Su Wen: Ling Lan Mi Dian Lun”, “The gallbladder is the official of righteousness, from which decisions are made,” indicating that gallbladder qi is related to a person’s mental and emotional activities, having a governing function in decision-making. Decision-making is part of mental activity, primarily governed by the heart, but the gallbladder also participates in the mental process, with its role being to govern decisions. The gallbladder’s function of decision-making is actually associated with the liver’s role in planning. Therefore, certain symptoms such as fear, insomnia, vivid dreams, and indecision are often attributed to gallbladder qi deficiency, and clinical treatment often focuses on the gallbladder. Although the gallbladder is one of the Six Fu organs, it stores essence and is a pure repository, not directly receiving food waste, which distinguishes it from other Fu organs, thus it is also classified as an Extraordinary Fu organ.
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2.The stomach governs the reception and ripening of food and fluids, facilitating harmony through descent
The stomach is located below the diaphragm, with its upper opening being the cardia, connecting to the esophagus, and its lower opening being the pylorus, leading to the small intestine. The stomach is also known as the “stomach cavity”; the ancient pronunciation of “cavity” is the same as “tube,” indicating a connection. Thus, the upper part of the stomach is the esophagus, and the lower part is the intestinal tube, with the stomach situated between the two, referred to as the “stomach tube (cavity)”. The stomach cavity is divided into three parts: the upper part is called the upper cavity, including the cardia; the middle part is called the middle cavity, known in Western medicine as the “stomach body”; the lower part is called the lower cavity, including the pylorus. Ancient anatomists observed that the stomach’s cavity is wide, capable of receiving a large amount of food and fluids at once, hence it is traditionally referred to as the “sea of food and fluids”. Since food and fluids are the source of qi and blood transformation in the body, and “people regard food as heaven,” the stomach is also called the “sea of food and fluid qi and blood”.
1. The stomach governs the reception and ripening of food and fluids
Reception refers to the act of accepting, containing, and actively ingesting. The primary physiological function of the stomach is to receive food and perform initial digestion, hence it is said that the stomach governs the reception and ripening of food and fluids.
“The stomach governs reception” means that food enters through the mouth, passes through the esophagus, and is contained within the stomach, which is a manifestation of the stomach’s physiological characteristics. The stomach’s ability to actively ingest and contain food relies on the function of stomach qi. Stomach qi governs smooth descent, allowing food to move downward; when food descends, the stomach empties, and when the stomach is empty, it can receive food again, thus generating appetite for further eating. If the stomach qi is damaged due to irregular eating habits, it may lead to symptoms such as loss of appetite or inability to retain food, resulting in vomiting. Conversely, if there is excessive heat in the stomach, food may be digested too quickly, leading to hunger shortly after eating, resulting in excessive intake, which over time can lead to thirst disorders.
Ripening implies initial processing and digestion. Food within the stomach undergoes grinding and digestive actions, transforming it into a semi-liquid state, making it easier for absorption and transport, and preparing it for further digestion in the small intestine.
The stomach’s reception and ripening, combined with the spleen’s transportation function, are referred to as “stomach qi.” The digestive function of the stomach (reception and ripening) is extremely important, as it is the prerequisite for the small intestine to receive and transform food and for the spleen to perform its transportation function, thus becoming the source of qi and blood transformation. Throughout history, physicians have emphasized the importance of protecting stomach qi. Hence, it is said, “With stomach qi, there is life; without stomach qi, there is death.”
2. Stomach qi descends to achieve harmony
The functional state of the stomach is to facilitate smooth descent. “Smooth” means unobstructed; “descent” means downward movement. The movement direction of stomach qi should be downward, allowing it to receive food from the esophagus and transmit it downward to the small intestine. After food enters the stomach and undergoes ripening, it moves into the small intestine for further digestion and absorption, with the turbid parts descending to the large intestine to form feces for excretion. Thus, it is said that the stomach governs descent, achieving harmony through descent.
The descending action of stomach qi is crucial not only for the stomach itself but also for the functional state of the entire Six Fu organ system, allowing all Fu organs to exhibit the characteristic of descent. The digestion and absorption of food is a complete process requiring close coordination and cooperation among the Six Fu organs. When the stomach is unobstructed, all are unobstructed; when the stomach descends, all descend. Hence, the ancients proposed the theory that “stomach qi descends to achieve harmony.”
Furthermore, the essence of food must be absorbed and distributed by the spleen, hence it is said that “the spleen carries the stomach’s fluids.” If, for some reason, the stomach’s reception, ripening, and descending functions are affected, the stomach’s digestive capacity will be compromised. Symptoms such as abdominal distension, poor appetite, and stomach pain indicate disharmony of stomach qi; symptoms such as nausea, vomiting, belching, and hiccups indicate upward reversal of stomach qi.
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3.The small intestine governs the reception and transformation of substances, distinguishing between clear and turbid
The small intestine is located in the abdomen, connecting above to the pylorus and communicating with the stomach; below, it connects to the cecum and the large intestine. The small intestine is a long, narrow tubular organ, coiled around the navel.
1. The small intestine governs the reception and transformation of substances
Reception refers to the act of containing substances, meaning to accept and hold. The small intestine receives the food that has been initially digested by the stomach (chyme), thus it serves as a container for the stomach’s contents. Food remains in the small intestine for a longer duration to facilitate further digestion, which is the “transformation” process. Through this further digestion, the original chyme transforms into a mixture of nutrients that can be absorbed by the body and food residues, allowing the food and fluids to be refined into essences that nourish the entire body. Thus, the “Su Wen: Ling Lan Mi Dian Lun” states: “The small intestine is the official of reception and transformation of substances.”
2. The small intestine governs the distinction between clear and turbid
Distinguishing between clear and turbid is the primary physiological function of the small intestine. The term “distinguishing between clear and turbid” means that the small intestine further digests the food that has been initially processed by the stomach, allowing the spleen to absorb the clear essence and most of the fluids, which is the “clear,” while the useless fluids and food residues are the “turbid,” which are then excreted through the kidneys into the bladder. Hence, there is also the saying that “the small intestine governs fluids.” The pathological changes in the small intestine primarily manifest as abnormalities in the digestive function of distinguishing between clear and turbid, leading to issues such as abdominal pain, diarrhea, and abnormal urination.
The functions of the small intestine in receiving and transforming substances and distinguishing between clear and turbid actually occur simultaneously. The process of distinguishing clear from turbid is also a manifestation of the spleen’s transportation function and the stomach’s descending function within the small intestine. Without the spleen’s transportation function, the absorption of fluids and nutrients cannot occur, and “distinguishing clear” cannot be achieved; without the stomach’s descending action, food residues (waste) cannot be transmitted downward to the large intestine, and “distinguishing turbid” cannot be realized.
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4.The large intestine governs the transmission and transformation of waste
The large intestine is also located in the abdomen, with its upper end at the cecum, connecting to the small intestine, and its lower end being the anus, also known as the “exit gate.” The primary physiological function of the large intestine is to transmit waste. “Transmit” means to convey; “guide” means to lead downward. Transmission refers to the large intestine receiving the food residues that have been distinguished as clear and turbid by the small intestine, absorbing excess fluids to form feces, and gradually guiding them downward for excretion through the anus. Thus, the “Su Wen: Ling Lan Mi Dian Lun” states: “The large intestine is the official of transmission and transformation.” In the process of transmitting waste, the large intestine also absorbs some fluids, hence it is also referred to as “the large intestine governs fluids.”
The smooth transmission of waste relies on the normal function of the large intestine itself, as well as the descending action of the stomach, the dispersing function of the lungs, and the vaporization function of the kidneys. Therefore, pathological changes in the large intestine primarily manifest as abnormalities in fecal excretion, such as constipation, dryness, and intestinal prolapse. Large intestine diseases can also affect the stomach, lungs, and other organs, leading to functional disorders.
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5.The bladder governs the storage and excretion of urine
The bladder is a sac-like organ located in the lower abdominal cavity, situated below the kidneys and in front of the large intestine. It connects above to the ureters and below to the urethra, opening at the front. Among the five zang and six fu organs, the bladder is positioned lowest, serving as the reservoir for excess fluids after metabolism.
The primary physiological function of the bladder is to store and excrete urine. The fluids ingested by the body, such as water and food liquids, are transformed into fluids through the combined actions of various organs, such as the dispersing and regulating function of the lungs, the healthy movement of the spleen, and the vaporization function of the kidneys. These fluids are distributed throughout the body, nourishing and moistening it. After the metabolism of these fluids, the remaining fluids are directed through the pathways of the San Jiao to the kidneys and bladder, transforming into urine, which is stored in the bladder. When the urine in the bladder reaches a certain volume, under the vaporization action of the kidneys, the bladder opens, allowing for timely and voluntary excretion. Thus, the “Su Wen: Ling Lan Mi Dian Lun” states: “The bladder is where fluids are stored; when vaporized, they can be released.”
The storage and excretion of urine by the bladder are closely related to the vaporization function of the kidneys. Storage pertains to the consolidating action of kidney qi, while excretion pertains to the unblocking action of kidney qi, collectively referred to as the “opening and closing” function of the kidneys. The opening and closing of kidney qi control the downward flow of urine into the bladder and enable the bladder to store urine to a certain volume before timely excretion. The vaporization of the bladder is, in fact, part of the vaporization function of the kidneys. Therefore, if the opening and closing of the kidneys are disordered, it can lead to symptoms such as “bladder dysfunction causing itching, or incontinence” (as stated in the “Su Wen: Xuan Ming Wu Qi”). The pathological manifestations of the bladder primarily include frequent urination, urgency, and pain; or difficulty urinating, residual urine, or even urinary retention; or incontinence, which, apart from bladder diseases, is often related to kidney diseases.
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6.The San Jiao governs the passage of qi and the movement of fluids
The San Jiao refers to the upper, middle, and lower Jiao, classified as one of the Six Fu organs in the theory of organ systems. The hand Shaoyang San Jiao meridian runs through the trunk, from the chest to the lower abdomen (following the San Jiao), connecting with many organs and meridians, and interlinking with the hand Jueyin Pericardium meridian.
Throughout history, there have been many different views on the San Jiao, leading to much debate. Our understanding of the location and functions of the San Jiao can be summarized in the following three points:
1. The San Jiao refers to the body’s regions, governing all qi and overseeing the qi mechanism and vaporization throughout the body.
According to this concept, the body and its internal organs are divided into three parts: the upper Jiao includes the chest, head, heart, and lungs; the middle Jiao includes the abdomen above the navel, as well as the spleen and stomach; the lower Jiao includes the abdomen below the navel, the genital area, and the liver and kidneys.
The San Jiao governs all qi, meaning that the San Jiao is closely related to the physiological activities of all organs, meridians, and tissues. “All qi” refers to all forms of qi in the body, such as the qi of the organs, meridian qi, respiratory qi, and nutritive and defensive qi. The San Jiao’s ability to govern all qi primarily stems from the Yuan qi. Yuan qi originates in the kidneys; how can it be distributed throughout the body? The San Jiao provides the pathways for its movement. The movement of Yuan qi can only be disseminated and reach all parts of the body through the pathways of the San Jiao, thus stimulating and promoting the functional activities of various organs and tissues, which is why the San Jiao plays a role in governing all qi. Therefore, the “Nan Jing: Sixty-six Difficulties” states: “The San Jiao is the separate envoy of Yuan qi.” Additionally, the Zong qi also descends from the San Jiao to support the innate qi, making the San Jiao the channel for the movement of fluids and the rise and fall of qi, serving as the driving force for the vaporization function, promoting the body’s metabolism, hence the saying that “the San Jiao oversees the qi mechanism and vaporization throughout the body.”
2. The San Jiao is the pathway for fluids.
The “Su Wen: Ling Lan Mi Dian Lun” states: “The San Jiao is the official of drainage, from which the pathways of fluids emerge.” This indicates that the primary function of the San Jiao is the vaporization of fluids and the unblocking of the pathways of water. The internal organs such as the lungs, spleen, kidneys, stomach, large intestine, small intestine, and bladder regulate the body’s fluid metabolism, collectively referred to as the qi transformation of the San Jiao. As stated in the “Ling Shu: Jue Qi,” “The upper Jiao develops, dispersing the flavors of the five grains, moistening the skin, nourishing the body, and benefiting the hair, like the irrigation of mist and dew, this is called qi.” The upper Jiao is like mist, which refers to the lung’s function of dispersing defensive qi and distributing fluids; in the “Ling Shu: Ying Wei Sheng Hui,” it states: “The middle Jiao also includes the stomach… separating waste, steaming fluids, transforming essences, and ascending to the lung meridian, thus transforming into blood…” The middle Jiao is like fermentation, which refers to the spleen and stomach’s function of transforming the essence of food and fluids, serving as the source of qi and blood transformation; “The lower Jiao separates the returning intestines, directing to the bladder… forming waste, and all descending to the large intestine… assisting in the secretion of fluids, following the lower Jiao and permeating into the bladder,” which refers to the small intestine’s governance of fluids, the large intestine’s governance of fluids, and the kidneys and bladder’s regulation of fluids and urine excretion, collectively referred to as the vaporization function.
3. The concept of differentiation in the San Jiao.
Differentiation in the San Jiao is one of the methods for diagnosing exogenous febrile diseases, extending the aforementioned theories about the San Jiao’s location and functions to the diagnosis of exogenous febrile diseases. Upper Jiao diseases include symptoms of external pathogens attacking the lungs, pathogens in the defensive layer, and external pathogens reversing to the pericardium, mostly belonging to the early stage of exogenous febrile diseases. Middle Jiao diseases include heat accumulation in the stomach and intestines and damp-heat in the spleen and stomach, mostly belonging to the mid-stage of exogenous febrile diseases; lower Jiao diseases include deep-seated pathogens, kidney yin deficiency, liver blood deficiency, and yin deficiency leading to wind, which are symptoms of the late stage of exogenous febrile diseases. This method of differentiation using the San Jiao has implications for determining the location of the disease and classifying the disease stage. Internal injuries and miscellaneous diseases sometimes also use San Jiao differentiation, combining the concepts and functions of the San Jiao, but not as systematically or specifically as in exogenous febrile diseases.
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7.The brain is the residence of the original spirit
The brain is located within the cranial cavity, connecting below to the spinal cord. The “Nei Jing” considers the brain to be one of the six Extraordinary Fu organs, characterized by its function of “storing but not leaking.” The Du meridian of the eight extraordinary vessels “runs along the spine, reaching the Fengfu, and enters the brain,” while the foot Taiyang bladder meridian “enters the brain from the crown.”
Although traditional Chinese medicine attributes the functions of human spirit, consciousness, and cognitive activities to the heart, and relates them to the liver and kidneys, it still recognizes certain functions of the brain. For instance, it is believed that “the brain is the sea of marrow, and all marrow belongs to the brain, thus from the brain to the tailbone, it is the pathway for the rise and fall of essence and marrow.” These statements indicate that the brain is the gathering place of human essence and marrow. Li Shizhen and Jin Zhengxi further clarified that “the brain is the residence of the original spirit” and “all human memory resides in the brain,” further explaining that human consciousness and cognitive activities are functions of the brain, and that bodily movements, vision, hearing, and other neurological activities are related to the brain. For example, the “Ling Shu: Hai Lun” states: “If the sea of marrow is insufficient, then the brain turns, causing tinnitus, weakness in the legs, dizziness, and inability to see clearly, leading to lethargy and sleepiness.”
From the perspective of organ theory, the physiology, pathology, and differentiation of the brain primarily belong to the heart, liver, and kidneys. “The heart houses the spirit” essentially refers to the brain’s mental activities and cognitive functions; symptoms such as “heat entering the pericardium” and “phlegm obstructing the heart orifices” are indicative of central nervous system symptoms; imbalances in the heart’s yin and yang and qi and blood can also lead to changes in brain function; while nourishing blood, calming the spirit, opening the orifices, transforming phlegm, nourishing heart yin, and warming heart yang can have certain effects on the central nervous system. The liver’s functions of “governing dispersal” and “governing tendons” also partially relate to brain functions; symptoms such as “liver qi stagnation” and “liver yang rising” can also be associated with the nervous system; the symptom of “liver wind stirring internally” is fundamentally a central nervous system symptom; and certain herbs that soothe the liver, pacify the liver, anchor yang, and calm wind can also have certain effects on the central nervous system. Since the kidneys store essence and generate bone marrow, and the brain is the sea of marrow, the relationship between the kidneys and the brain is particularly close. Insufficient kidney essence can hinder the brain’s development in infants and lead to cognitive decline in adults or the elderly. Practical evidence shows that certain kidney-tonifying herbs can improve brain function.
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8.The uterus governs menstruation and the nurturing of the fetus
The uterus, also known as the womb or female organ, is located in the center of the lower abdomen, behind the bladder and in front of the rectum, connecting to the vagina at its lower opening. When not pregnant, it resembles an inverted pear and is also one of the six Extraordinary Fu organs. It is the organ responsible for menstruation and nurturing the fetus. However, the onset of menstruation and the nurturing of the fetus are also related to the following three factors.
1. The role of kidney essence
The female reproductive organs require the fullness of kidney essence to develop and mature; the onset of menstruation prepares the conditions for nurturing the fetus. As women age and kidney essence declines, menstruation ceases, and reproductive capacity diminishes. As stated in the “Su Wen: Shang Gu Tian Zhen Lun”: “At seven years old, kidney qi is abundant, teeth and hair grow. At fourteen, the heavenly essence (Tian Gui, a part of kidney essence related to reproductive function) arrives, the Ren meridian opens, and the Chong meridian flourishes, leading to timely menstruation and the ability to conceive. At twenty-one, the Ren meridian weakens, the Chong meridian declines, the heavenly essence is exhausted, and the pathways are blocked, leading to physical decline and infertility.” This indicates that kidney essence is a fundamental condition for maintaining normal menstruation and nurturing the fetus.
2. The role of the Chong and Ren meridians
The Chong meridian and Ren meridian both originate in the womb, with the Ren meridian meeting the foot’s three yin meridians in the lower abdomen, regulating all the yin meridians, hence it is called the “sea of yin meridians”; the Chong meridian runs parallel to the kidney meridian, regulating the qi and blood of the twelve meridians, hence it is called the “sea of blood.” The qi and blood of the twelve meridians fill the Chong and Ren meridians, and through the regulation of the Chong and Ren, they enter the uterus, forming menstruation. In youth, due to insufficient kidney qi, the uterus does not develop; ancient scholars believed that the Ren meridian was not open and the Chong meridian was not flourishing, hence menstruation does not occur; around the age of fifty, due to the gradual decline of kidney essence, the Chong and Ren meridians become insufficient, leading to menstrual irregularities and eventual cessation, which is a physiological phenomenon. If the Chong and Ren meridians are imbalanced, it can lead to menstrual cycle irregularities.
3. The role of the heart, liver, and spleen
The heart governs blood, the liver stores blood, and the spleen regulates blood, thus they are related to the onset of menstruation. If the liver does not store blood or the spleen does not regulate blood, it can lead to excessive menstruation, shortened cycles, prolonged periods, and conditions such as blood flooding and leakage, collectively referred to as “liver and spleen dysfunction in blood storage and regulation.” If the spleen is deficient and cannot transform the essence of food and fluids, leading to insufficient blood production; or if emotional disturbances affect the heart, resulting in insufficient heart blood, symptoms such as reduced menstrual flow, prolonged cycles, or even amenorrhea can occur, referred to as “deficiency of both heart and spleen.” Additionally, emotional depression affecting the liver’s dispersing function can also lead to menstrual irregularities due to liver qi stagnation.
In summary, the onset of menstruation is not due to a single factor but is related to the overall condition of the body and mental factors. However, the primary factors are the interplay of kidney essence, liver dispersal, and the regulation of the Chong and Ren meridians, which together maintain a normal menstrual cycle and prepare favorable conditions for nurturing the fetus.
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