Traditional Chinese Medicine categorizes the important internal organs of the human body into two main types: the “Zang” (organs) and “Fu” (bowels). The theory regarding these organs is known as the “Zangxiang” (藏象) theory. “Zang” refers to the internal organs that are hidden within, while “xiang” refers to manifestations or images. This means that although the internal organs exist within the body, their physiological and pathological changes are reflected externally. Therefore, the study of Zang and Fu in TCM is a theory that examines the laws of internal organ activities and their interrelationships through the observation of external manifestations of the human body.The distinction between Zang and Fu is based on the different functions of the internal organs. The Zang organs include the heart (Xin), liver (Gan), spleen (Pi), lungs (Fei), and kidneys (Shen) (五脏), which mainly refer to certain organs filled with internal tissues in the thoracic and abdominal cavities, and their common function is to store vital essence (精气). Vital essence refers to the essential nutrients that nourish the Zang and Fu organs and sustain life activities. The Fu organs include the gallbladder (Dan), stomach (Wei), large intestine (Da Chang), small intestine (Xiao Chang), bladder (Pang Guang), and San Jiao (三焦) (六腑), which mostly refer to hollow organs in the thoracic and abdominal cavities that have the functions of digesting food, absorbing nutrients, and excreting waste. Additionally, there are the “extraordinary Fu” (奇恒之腑), which refers to a category of organs outside the five Zang and six Fu that have physiological functions different from ordinary Fu, including the brain (Nao), marrow (Sui), bones (Gu), vessels (Mai), and uterus (Zi Nu). It should be noted that in TCM, Zang and Fu not only refer to the anatomical organs but are more importantly a summary of the physiological functions and pathological changes of the human body. Therefore, although the names of the organs in TCM are mostly the same as those in modern medicine, their concepts and functions are not entirely consistent, and thus they cannot be equated.The Correspondence of the Five Elements and the Human BodyThe Five Elements are wood (Mu), fire (Huo), earth (Tu), metal (Jin), and water (Shui), representing five attributes and are abstract concepts, not to be understood as specific entities. The number five is universal, as seen in five fingers, five senses, five organs, and five tastes, with many things categorized into five types.In TCM, the Five Elements describe the functions and relationships of the five Zang organs (liver, heart, spleen, lungs, kidneys), noting that these Zang organs are also functional concepts (referred to as Zangxiang) and are not limited to the specific anatomical Zang organs.Wood – growth, development, gentleness, smoothnessFire – warmth, rising, brightnessEarth – transformation, bearing, receivingMetal – cleanliness, purification, convergenceWater – coldness, moisture, downward movement
Things in the same line interact with each other, but excess can cause harm. For example, anger can harm the liver. The story of Fan Jin passing the imperial examination is a typical example of excessive joy harming the heart. Similarly, an appropriate sweet flavor can tonify the spleen, but excessive sweetness can stagnate the stomach and spleen.The Generating and Overcoming Relationships of the Five ElementsSolid lines indicate generating; dashed lines indicate overcoming.Generating refers to one thing promoting, enhancing, and nurturing another (for convenience of discussion, the generator is called the mother, and the generated is called the child). Overcoming refers to one thing inhibiting and restraining the growth and function of another. Generating and overcoming are normal phenomena that exist universally in nature. Without generation, there is no development; without restraint, there is excess and harm. Both are important; do not think that generating is good and overcoming is bad. Gigantism is a case where growth lacks restraint.Generating and overcoming are inseparable aspects. Without generation, there is no occurrence and growth of things; without overcoming, there can be no balance and coordination in the development and change of things.The Relationships Among the Five Zang Organs(1) The generating relationship among the five Zang organs: the liver generates the heart, which is wood generating fire, as the liver stores blood to nourish the heart; the heart generates the spleen, which is fire generating earth, as the yang energy of the heart can nourish the spleen; the spleen generates the lungs, which is earth generating metal, as the spleen transforms the essence of food and water to benefit the lungs; the lungs generate the kidneys, which is metal generating water, as the clear energy of the lungs helps the kidneys; the kidneys generate the liver, which is water generating wood, as the kidneys store essence to nourish the liver’s yin blood, etc.(2) The overcoming relationship among the five Zang organs: the clear and purifying function of the lungs (metal) can inhibit the excessive yang of the liver (wood), that is, metal overcomes wood; the smooth function of the liver (wood) can relieve the stagnation of the spleen (earth), that is, wood overcomes earth; the transforming function of the spleen (earth) can prevent the flooding of the kidneys (water), that is, earth overcomes water; the yin of the kidneys (water) can restrain the excessive yang of the heart (fire), that is, water overcomes fire; the yang heat of the heart (fire) can restrain the excessive clearing of the lungs (metal), that is, fire overcomes metal.However, it must be pointed out that the theory of the Five Elements to explain the balance relationship among the Zang and Fu has certain limitations. This is because the correspondence of the five Zang organs to the Five Elements only extracts some characteristics of the Zang organs, and the Five Elements cannot explain all phenomena in the world; they only represent partial relationships.The Mutual Influence of Diseases Among the Five Zang Organs(1) Maternal disease affecting the child: when the mother organ is sick, it can then affect the child organ.(2) Child disease affecting the mother: when the child organ is sick, it can then affect the mother organ. In this case, the condition is generally more severe.(3) Mutual increase: that is, excessive overcoming. This may be due to the overcoming entity being too strong or the affected entity being too weak. In this case, the condition is likely to become serious.(4) Mutual insult: that is, insufficient overcoming, leading to being overcome. This may be due to the affected entity being too strong or the overcoming entity being too weak.The Relationship Between the Five Zang Organs and the SeasonsWood corresponds to spring, fire corresponds to summer, earth corresponds to late summer, metal corresponds to autumn, and water corresponds to winter. In each season, the corresponding Zang organ bears a heavier burden, while the Zang organ that generates it receives nourishment. For example, liver diseases are prone to occur in spring because wood generates fire, placing a heavy burden on the liver. At the same time, since wood generates fire (heart), the mood is easily uplifted.The Strength and Weakness of the Five Zang Organs and Their Relationship to PersonalityIn terms of personality, if the generating and overcoming of the Five Elements are unbalanced, excessive fire without restraint leads to impatience and lack of cultivation. Excessive water without restraint leads to cleverness but weak will and restlessness. Excessive wood without restraint leads to obstinacy. Excessive metal without restraint leads to efficiency and sharpness. Excessive earth without restraint leads to kindness and a preference for tranquility. Of course, even in such cases, through self-control, one can still achieve personality balance.
The Heart Among the Five Zang OrgansThe heart is located in the left side of the thoracic cavity, above the diaphragm and below the lungs, round and pointed at the bottom, resembling a lotus bud, protected by the pericardium. The heart forms a system with the small intestine, vessels, face, tongue, etc. In the Five Elements, the heart belongs to fire, being the most yang organ, governing blood vessels, housing the spirit, and being the ruler of the five Zang and six Fu, the master of life. The heart corresponds to the summer season.Physiological Functions of the Heart:1. The heart governs blood vessels.This means the heart has the role of managing blood and promoting blood circulation in the vessels, including both governing blood and governing vessels. Blood refers to blood, while vessels refer to blood vessels, also known as meridians, which are the channels for blood circulation. The heart and blood vessels are connected, forming a closed system that serves as the hub of blood circulation. The heart’s rhythmic beating requires three conditions: abundant heart qi, sufficient blood, and unobstructed vessels.2. The heart houses the spirit.The meaning of spirit: in TCM, the spirit has three main meanings: first, it refers to the functions and laws of material movement and change in nature. The so-called “Yin and Yang are unpredictable, referred to as spirit” (《素问·天元纪大论》). Second, it refers to the totality of life activities in the human body, generally called the broad sense of spirit. The external manifestations of the entire body’s life activities, such as the overall image of the body, complexion, eye spirit, speech, responses, and body movements, all fall within the scope of spirit. In other words, all external manifestations of the body are reflections of its life activities. Third, it refers to people’s mental, conscious, and thinking activities, generally called the narrow sense of spirit. Vital essence is the material basis for producing spirit. The physiological functions of the heart in housing the spirit have two aspects: first, it governs thinking, consciousness, and spirit. Under normal circumstances, the clear heart receives and reflects objective external things, engaging in mental, conscious, and thinking activities. Second, it governs life activities. “The heart is the ruler of the body, the root of all things” (《饮膳正要·序》). The clear heart is the master of life activities in the human body. The five Zang and six Fu must operate under the unified command of the heart to carry out coordinated normal life activities. The heart is the monarch, and all organs and bones obey the heart. The heart houses the spirit and serves the purpose of the spirit. “The heart is the great master of the five Zang and six Fu, the dwelling of the spirit” (《灵枢·邪客》).The physiological characteristics of the heart: the heart is a yang organ and governs clarity. The heart is the sun among the yang organs, utilizing yang energy. The yang heat of the heart not only maintains the physiological functions of the heart itself but also has a nourishing effect on the entire body.The relationship of the heart with form, orifices, will, fluids, and time:The heart is associated with the vessels, its manifestation is in the face.The heart is associated with the tongue.The heart is associated with joy.The heart is associated with sweat.The heart corresponds to summer heat.The heart externally corresponds to the chest. “The heart is the official of the monarch, from which the spirit emerges.”
The Lungs Among the Five Zang OrgansThe lungs are located in the chest, one on each side, lobed in shape and of loose texture. They reside above the diaphragm, connect to the trachea, and open to the nose, directly communicating with the atmosphere.Physiological Functions of the Lungs: The lungs govern qi, control respiration, govern water, and regulate the hundred vessels.1. The lungs govern qi: (1) The lungs govern the qi of the entire body. This means the lungs have the role of presiding over and regulating the qi of all Zang and Fu organs, participating in the generation of qi through respiration and regulating the qi mechanism. (2) The lungs govern the qi of respiration. The lungs are the site of gas exchange between the internal and external environments, meaning the lungs inhale the clear qi from the environment and exhale the turbid qi from the body, achieving the function of gas exchange.2. The lungs govern water: This refers to the lungs’ role in the distribution, movement, and excretion of body fluids through their dispersing and descending functions. As the highest organ, the lungs participate in regulating the body’s fluid metabolism, hence it is said that “the lungs are the upper source of water” (《血证论‘肿胀》). 3. The lungs govern the hundred vessels: All blood vessels converge and flow through the lungs, and through the lungs’ respiration, gas exchange occurs, thus it is said that the lungs govern the hundred vessels.4. The lungs govern regulation: Regulation refers to governance and adjustment. The lungs assist the heart in regulating and adjusting the qi, blood, fluids, and physiological functions of all Zang and Fu organs. The heart is the official of the monarch, while the lungs are the assisting official. The activities of all Zang and Fu organs depend on the lungs’ assistance to the heart for governance and regulation. Therefore, the lungs are called the “assisting official.”The regulatory functions of the lungs are mainly reflected in four aspects:(1) The lungs govern respiration: The rhythmic movement of the lungs in inhalation and exhalation plays a crucial role in ensuring smooth breathing.(2) Regulating the qi mechanism: The lungs govern qi, regulating the rise and fall of qi, ensuring smooth qi movement throughout the body. It is said that “the lungs govern qi; when the qi is regulated, the Zang and Fu organs are treated” (《类经·脏象类》).(3) Assisting the heart in blood circulation: The lungs govern the hundred vessels, assisting the heart in circulating blood, promoting and regulating the movement of blood throughout the body. “All qi belongs to the lungs”; when qi moves, blood also moves.(4) Dispersing and descending: The lungs’ dispersing and descending functions govern and regulate the distribution, movement, and excretion of fluids. Therefore, the lungs’ regulatory function is a high-level summary of their main physiological functions.The Physiological Characteristics of the Lungs:1. The lungs are the canopy: The canopy refers to an umbrella. The term originally referred to the cover of ancient emperors’ carriages. The lungs are the canopy, meaning they are the highest organ in the body cavity, protecting the other organs and resisting external pathogens. The lungs are located in the thoracic cavity, at the highest position among the five Zang organs, serving to cover the other organs, and they also govern the body’s exterior, thus they are called the canopy. 2. The lungs are delicate organs: The lungs are delicate organs, meaning they are clear, empty, and tender, making them susceptible to external pathogens. The lungs are a clear and empty organ, and being at a high position, they are the canopy of the other organs, the convergence of the hundred vessels, and directly communicate with the weather; external pathogens can easily invade the lungs, causing disease. The cold and heat changes in other organs often affect the lungs, as they are intolerant to cold and heat and are easily invaded, hence they are called delicate organs.The relationship of the lungs with form, orifices, will, fluids, and time:The lungs are associated with the skin, their manifestation is in the hair.The lungs are associated with the nose, and the throat is the portal of the lungs.The lungs are associated with grief and worry.The lungs are associated with nasal mucus.The lungs correspond to autumn heat.The lungs externally correspond to the abdomen. “The lungs are the assisting official, from which regulation emerges.”
The Spleen Among the Five Zang OrgansThe spleen is located in the upper abdomen, beneath the diaphragm, connected to the stomach by a membrane, “shaped like a dog’s tongue, resembling a chicken comb,” and forms a system with the stomach, flesh, lips, and mouth.Physiological Functions of the Spleen: The spleen governs transportation and transformation, and it governs blood.1. The spleen governs transportation and transformation: Transportation refers to the movement and delivery, while transformation refers to digestion and absorption. The spleen’s function of transportation and transformation means that it can convert food and water into essence and transport the essence to all Zang and Fu organs. In fact, the spleen is responsible for the digestion, absorption, and transportation of nutrients. This includes the transportation of food and the transformation of body fluids.(1) Transportation of food: Food refers to various types of food and drink. The spleen’s transportation of food means its role in digesting and absorbing food. The process of the spleen’s transportation of food is as follows: first, the food that has been initially digested by the stomach is further processed by the small intestine, and through the spleen’s grinding and digestion, it is transformed into the essence of food (also known as food essence); second, the spleen absorbs the food essence and transports it to the entire body; third, the food essence is sent to the heart and lungs to be transformed into qi and blood, which are vital substances for life. In summary, the spleen’s function of transporting food includes the digestion of food, absorption of essence, and transformation of essence into qi and blood.(2) Transportation of body fluids: The transportation of body fluids, also known as the transportation of water, refers to the spleen’s role in absorbing and transporting body fluids, regulating the body’s fluid metabolism, meaning the spleen works with the lungs, kidneys, San Jiao, and bladder to regulate and maintain the balance of the body’s fluid metabolism. The spleen’s function of transporting body fluids is a key link in regulating the body’s fluid metabolism. In the process of fluid metabolism, while the spleen transports food essence, it also delivers the necessary body fluids (fluids) to nourish and moisten all tissues through the heart and lungs, and it promptly transports the used fluids back to the kidneys, where they are transformed into urine and excreted, thus maintaining the balance of fluid metabolism in the body. The spleen is located in the middle Jiao, serving as the hub for the rise and fall of qi in the body, thus playing an important role in the process of fluid metabolism. Therefore, when the spleen’s function of transporting body fluids is strong, it can ensure that all tissues receive sufficient moisture without excessive retention of fluids. Conversely, if the spleen’s function is impaired, it will lead to stagnation of fluids in the body, resulting in pathological products such as dampness and phlegm, and even edema.2. The spleen governs blood: The spleen governs blood, meaning it has the function of controlling blood, ensuring it flows within the vessels without overflowing. The spleen’s qi can control the blood throughout the body, allowing it to circulate normally without spilling outside the vessels. The spleen’s function of governing blood is achieved through the qi’s control over blood. The spleen is the source of the generation of qi and blood; qi is the commander of blood, and blood follows qi. When the spleen’s transportation function is strong, qi and blood are abundant, and qi can control blood; when qi is strong, the controlling function is also strong, and blood will not escape from the vessels, leading to bleeding. Conversely, if the spleen’s transportation function declines, the source of transformation is insufficient, leading to qi and blood deficiency, and qi deficiency will result in a lack of control, causing blood to leave the vessels, leading to bleeding. Thus, the spleen’s governance of blood is a concrete manifestation of the relationship between qi and blood, as stated, “The spleen governs blood, meaning blood flows according to the spleen’s qi” (《医碥·血》).The Physiological Characteristics of the Spleen:1. The spleen’s qi governs rising. The spleen’s nature is to rise, meaning the movement of the spleen’s qi is primarily upward; when the spleen rises, its qi is strong. The spleen’s qi maintains the relative position of the organs.2. The spleen prefers dryness and dislikes dampness. The spleen governs dampness and dislikes dampness because dampness harms the spleen, causing it to lose its healthy function, leading to dampness in the patient, referred to as “dampness obstructing the spleen’s earth.”The relationship of the spleen with form, orifices, will, fluids, and time:The spleen is associated with flesh, governing the four limbs. Its manifestation is in the lips.The spleen is associated with the mouth.The spleen is associated with thought.The spleen is associated with saliva.The spleen corresponds to late summer.The spleen externally corresponds to the lower abdomen. “The spleen is the official of advice, knowing the surroundings.”
The Liver Among the Five Zang OrgansThe liver is located in the abdomen, beneath the diaphragm, and slightly to the left of the right rib. It forms a system with the gallbladder, eyes, tendons, and nails, governing smoothness, storage, joy, and disliking depression, being yin with yang. In the Five Elements, it belongs to wood, being the yang among the yin organs. The liver corresponds to the spring season.Physiological Functions of the Liver: The liver governs smoothness and blood storage.1. The liver governs smoothness: This means the liver has the role of smoothing, relaxing, and ensuring the smooth flow of qi throughout the body, preventing stagnation and ensuring dispersal. The main role of the liver’s smoothness in physiological activities is:(1) Regulating qi movement: The liver’s smoothness is crucial for the smooth flow of qi throughout the body. Qi movement refers to the rise and fall of qi, which is the basic form of qi transformation. The human body is a system that continuously undergoes the rise and fall of qi movement. The process of qi movement is achieved through the functional activities of the Zang and Fu organs. The interconnection of the body’s Zang and Fu organs, qi, blood, body fluids, and yin-yang relies on the smooth rise and fall of qi, and the liver’s smoothness plays an important role in maintaining the balance and coordination of qi movement among the Zang and Fu organs. “All qi transformations of the Zang and Fu organs must rely on the qi transformation of the liver and gallbladder to be stimulated, in order to be smooth and not diseased” (《读医随笔·卷四》). Therefore, when the liver’s smoothness is normal, qi movement is smooth, qi and blood are harmonized, and the activities of the Zang and Fu organs are coordinated.(2) Regulating emotions: Emotions refer to feelings and moods, which are a type of psychological process primarily reflecting emotional changes. In TCM, emotions fall under the narrow sense of spirit, including joy, anger, worry, thought, sadness, fear, and surprise, also known as the seven emotions. The liver can regulate emotional activities through its smoothness.(3) Promoting digestion and absorption: The spleen and stomach are the main digestive organs in the body. The stomach governs receiving, while the spleen governs transportation. The liver’s smoothness is an important condition for maintaining normal digestion and absorption in the spleen and stomach. The liver promotes the spleen and stomach’s digestive and absorptive functions by coordinating the rise and fall of qi in the spleen and stomach and secreting and excreting bile.(4) Maintaining the movement of qi and blood: The liver’s smoothness can directly affect the smoothness of qi movement. Only when qi movement is smooth can the heart’s role in governing blood vessels, the lungs’ assistance to the heart in circulating blood, and the spleen’s governance of blood be fully realized, thus ensuring the normal movement of qi and blood.(5) Regulating fluid metabolism: The regulation of fluid metabolism is mainly completed by the lungs, spleen, kidneys, and other organs, but it is also closely related to the liver. The liver governs smoothness, which can regulate the qi movement of the San Jiao, promoting the functions of the lungs, spleen, and kidneys in regulating fluid metabolism, that is, by promoting the spleen’s transportation of body fluids, the lungs’ distribution of fluids, and the kidneys’ transformation of fluids to regulate fluid metabolism. The San Jiao serves as the channel for fluid metabolism. “If the upper Jiao is not treated, water will invade the high source; if the middle Jiao is not treated, water will remain in the middle; if the lower Jiao is not treated, water will disrupt the two excretions. When the qi of the San Jiao is treated, the vessels will be smooth, and the water channels will be unblocked” (《类经，脏象类》). The function of the San Jiao in managing the flow of fluids is essentially a comprehensive function of the lungs, spleen, kidneys, and other organs in regulating fluid metabolism. The liver’s smoothness ensures that qi movement is smooth, thus facilitating the movement of fluids throughout the body, which is the theoretical basis for regulating water through qi.(6) Regulating sexuality and reproduction: (1) Regulating the Chong and Ren meridians: Women’s special physiological activities, such as menstruation, pregnancy, and childbirth, involve the functions of many organs, among which the liver plays a very important role, hence the saying, “Women regard the liver as their innate foundation.” (2) Regulating the essence chamber: The essence chamber is where men store their essence. When men’s kidney qi is abundant, the essence can overflow, enabling reproductive capability. The opening and closing of the essence chamber and the storage and release of semen are related to the functions of the liver and kidneys. “The one that governs closure and storage is the kidney, while the one that governs smoothness and release is the liver” (《格致余论·阳有余阴不足论》).2. The liver governs blood: The liver’s blood storage refers to its ability to store blood, prevent bleeding, and regulate blood volume. Therefore, it is known as the “sea of blood.”(1) Storing blood: Blood originates from the essence of food and is transformed by the spleen and stored in the liver. The liver stores a certain amount of blood, which can nourish itself, restrain the liver’s yang energy, and maintain the balance of yin and yang in the liver, as well as harmonize qi and blood. If the liver does not store blood, it can lead to insufficient liver blood and excessive rising of yang energy, which can also result in bleeding.(2) Regulating blood volume: Under normal physiological conditions, the blood volume in different parts of the body is relatively constant. However, the blood volume in different parts of the body often changes with different physiological conditions. When the body is under intense activity or emotional excitement, the demand for blood in various parts of the body increases, and the blood stored in the liver is distributed to the periphery to meet the body’s needs. When people are at rest and their emotions are stable, the activity level of various parts of the body decreases, and the demand for blood in the periphery also decreases, leading to some blood returning to the liver. It is said that “when a person is active, blood flows through the meridians; when a person is at rest, blood returns to the liver.” Because the liver has the function of storing blood and regulating blood volume, it is referred to as the “sea of blood.”The Physiological Characteristics of the Liver:1. The liver prefers smoothness: Smoothness refers to the idea of being relaxed, open, and unobstructed. Depression refers to obstruction and stagnation. The liver, being the organ of wind and wood, prefers smoothness and dislikes depression. The liver’s qi should remain gentle and smooth to maintain its normal physiological functions.2. The liver is a strong organ.The relationship of the liver with form, orifices, will, fluids, and time:The liver is associated with tendons, its manifestation is in the nails.The liver is associated with the eyes.The liver is associated with anger.The liver is associated with tears.The liver corresponds to spring heat.The liver externally corresponds to the two sides of the abdomen. “The liver is the official of the general, from which strategies emerge.”
The Kidneys Among the Five Zang OrgansThe physiological functions of the kidneys: The kidneys store essence, govern the reception of qi, and govern water.1. The kidneys store essence: The kidneys’ storage of essence refers to their role in storing and safeguarding the essence of the human body. The physiological functions of essence: The essence in the kidneys not only promotes growth, development, and reproduction but also participates in blood production, enhancing the body’s resistance to disease. (1) Promoting reproduction: Kidney essence is the original substance for embryonic development and can promote the maturation of reproductive functions. The generation, storage, and release of kidney essence play an important role in reproduction. The development of the male and female reproductive organs and their reproductive capabilities depend on the abundance of kidney essence, thus the saying, “The kidneys govern reproduction.” Based on this theory, preserving kidney essence becomes one of the important methods for treating reproductive and sexual dysfunction. (2) Promoting growth and development: Life follows the natural laws of birth, growth, maturity, aging, and death. The time from birth to aging and death is called lifespan, usually measured by age. (3) Participating in blood production: The kidneys store essence, and essence can transform into marrow, which can then become blood. “Blood is a part of essence, but essence is stored in the kidneys, and while it is not abundant, blood is rich in circulation” (《景岳全书，血证》). “Blood is the essence of food and is transformed by the true fire of the Mingmen” (《读医随笔·气血精神论》). Therefore, it is said that the source of blood is in the kidneys. Thus, in clinical practice, methods to tonify essence and marrow are often used to treat blood deficiency. (4) Resisting external pathogens: Kidney essence has the ability to resist external pathogens, preventing diseases. “Those with sufficient essence do not fall ill, while those with insufficient essence are prone to all kinds of diseases” (《冯氏锦囊秘录》). When essence is abundant, vitality is strong, and the body’s defenses are firm, making it difficult for pathogens to invade. Conversely, when essence is deficient, vitality weakens, defenses are compromised, and pathogens can invade, leading to illness. Therefore, it is said that “those who store essence do not fall ill in spring” (《素问·金匮真言论》). If essence is not stored in winter, illness will occur in spring; the kidneys’ ability to resist external pathogens falls under the category of righteous qi, which is similar to the meaning of “when righteous qi is present, pathogens cannot invade” and “wherever pathogens gather, qi must be deficient.”2. The kidneys govern water: Water refers to the normal fluids in the body. The kidneys govern water, broadly speaking, meaning they are the water organ, referring to the kidneys’ role in storing essence and regulating water. In a narrow sense, it refers to the kidneys’ function of presiding over and regulating the body’s fluid metabolism.3. The kidneys govern the reception of qi: Reception refers to the ability to capture and receive. The kidneys govern the reception of qi, meaning they have the role of capturing the qi inhaled by the lungs and regulating respiration. Although the lungs govern respiration, the inhaled qi must descend to the kidneys, where the kidney qi captures it, allowing for smooth and regulated breathing. “Qi roots in the kidneys and also returns to the kidneys, hence it is said that the kidneys govern qi, and their breath is deep” (《医碥·气》). “The lungs govern qi, while the kidneys govern the root of qi; the lungs govern exhalation, while the kidneys govern inhalation; yin and yang intersect, and breathing is harmonious” (《类证治裁·卷之二》).The physiological characteristics of the kidneys: The kidneys govern closure and storage: closure, also known as sealing and storage, refers to the ability to securely store and safeguard. The kidneys’ role in closure refers to their ability to store the essence of the five Zang and six Fu organs. Closure is an important physiological characteristic of the kidneys. The kidneys are the source of innate essence, the root of life, storing true yin and housing original yang, being the water and fire organs. The kidneys store essence, which should be preserved and not leaked; the kidneys govern the Ming fire, which should be hidden and not exposed. The source of human life comes from the kidneys, growth and development depend on the kidneys, and life activities rely on the kidneys. The kidneys are where the body’s yin essence gathers, and when kidney essence is abundant, the source of transformation is sufficient.The relationship of the kidneys with form, orifices, will, and fluids:The kidneys are associated with bones, producing marrow, and their manifestation is in the hair.The kidneys are associated with the ears and the two yin.The kidneys are associated with fear.The kidneys are associated with saliva.The kidneys correspond to winter heat.The kidneys externally correspond to the lower back. “The kidneys are the official of strength, from which skills emerge.”
The Six BowelsThe six organs in the human body include the gallbladder, stomach, large intestine, small intestine, San Jiao, and bladder. The term “Fu” (腑) originally referred to a storehouse. The main physiological function of the six Fu is to receive, digest food, separate the clear from the turbid, transform the essence, and excrete waste without allowing it to remain. Therefore, the six Fu should function smoothly and unobstructed. The specific physiological functions of the six Fu are: food enters the stomach, is digested by the stomach, moves down to the small intestine for further digestion, separates the clear from the turbid, absorbs the essence, and the large intestine receives the food residue from the small intestine, absorbs excess water, and the remaining waste is excreted as feces through drying and transportation. During the digestion and absorption of food, the gallbladder secretes bile into the small intestine to assist in digestion. The San Jiao not only serves as a channel for transformation but also plays a crucial role in managing the qi, facilitating the normal functioning of the transformation process.The GallbladderThe gallbladder is attached to the short lobe of the liver, connected to the liver, and is a hollow, sac-like organ. The gallbladder is one of the six Fu and also one of the extraordinary Fu.Its main functions are:1. Storing and excreting bile, which is bitter and yellow-green, and plays a role in promoting the digestion and absorption of food. Bile is transformed from the essence of the liver and stored in the gallbladder, hence it is called the “storehouse of essence” and “the house of purity.” The excretion of bile relies on the regulation and control of the liver’s smoothness. When the liver’s smoothness is normal, bile excretion is smooth, and the spleen and stomach’s functions are robust. If the liver’s qi is stagnant, bile excretion is hindered, affecting the digestive function of the spleen and stomach, leading to symptoms such as fullness in the chest and ribs, loss of appetite, or irregular bowel movements. If the liver’s smoothness is excessive, bile qi may reverse, leading to symptoms such as bitterness in the mouth and vomiting of yellow-green bile. If damp-heat accumulates in the liver and gallbladder, bile may overflow into the skin, resulting in jaundice. If bile excretion is obstructed for a long time, it can lead to the accumulation of stones.2. Governing decision-making: Decision-making belongs to the realm of thought. The gallbladder governs decision-making, meaning it has the role of judging matters and making decisions. This function is important for defending against and eliminating the adverse effects of certain mental stimuli, maintaining and controlling the normal flow of qi and blood, and ensuring the coordination among the Zang and Fu organs. Clinically, individuals with insufficient gallbladder qi are often easily startled, fearful, and indecisive.The StomachThe stomach is located below the diaphragm, connecting to the esophagus above and the small intestine below. The upper opening of the stomach is the cardia, and the lower opening is the pylorus. The stomach is divided into three parts: upper, middle, and lower, hence it is also called the stomach cavity.The main functions of the stomach are: 1. Governing the reception and digestion of food. Reception means accepting and accommodating; digestion refers to the process of the stomach initially digesting food into chyme. The stomach governs the reception and digestion of food, meaning it can accommodate food transmitted from the esophagus and initially digest it before passing it to the small intestine, hence the stomach is known as the “sea of food and drink” and “the granary.” The stomach’s reception and digestion provide the material basis for the spleen’s transportation function. Therefore, the spleen and stomach are often referred to as the “foundation of postnatal life, the source of qi and blood transformation,” and the functions of the spleen and stomach are summarized as “stomach qi.” The source of postnatal nutrition is closely related to the strength of “stomach qi,” and clinically, the strength of “stomach qi” is often used as an important basis for judging the severity of diseases and prognosis, with treatment focusing on “preserving stomach qi.” If the stomach’s reception and digestion functions are impaired, symptoms such as stomach distension and pain, loss of appetite, acid regurgitation, and hunger after eating may occur; if stomach qi is severely damaged, it becomes difficult to ingest food, leading to a poor prognosis, and in severe cases, the loss of stomach qi can be life-threatening, hence the saying, “A person lives with stomach qi; without stomach qi, one dies.” 2. Governing descent: Descent refers to the smooth downward movement of stomach qi. Food enters the stomach, is digested, and then descends to the small intestine for further digestion and absorption, with the clear being transported by the spleen and the turbid being passed to the large intestine for excretion. This entire process relies on the stomach’s “descent” function. Therefore, the stomach’s governing descent means it can pass chyme down to the small and large intestines and excrete waste. If the stomach fails to descend, it not only reduces appetite but also causes turbid qi to rise, leading to symptoms such as bad breath, abdominal distension and pain, acid regurgitation, hiccups, constipation, and even nausea and vomiting.The Small IntestineThe small intestine is located in the abdomen, connecting to the stomach above through the pylorus and to the large intestine below through the ileocecal valve. It is a hollow, tubular organ, coiled and folded. Its main functions are: 1. Governing reception and transformation. Reception means accepting and accommodating. The small intestine receives food that has been initially digested by the stomach, serving as a container; it also allows the food to remain for a period for further digestion and absorption. Transformation refers to the digestion and change, meaning the small intestine further digests and absorbs the chyme, transforming food into essence. If the small intestine’s functions of reception and transformation are impaired, symptoms such as abdominal distension, abdominal pain, diarrhea, or loose stools may occur. 2. Separating the clear from the turbid: The small intestine separates the clear from the turbid, meaning it can distinguish and separate the essence from the waste.The Large IntestineThe large intestine is located in the abdominal cavity, connecting to the small intestine above through the ileocecal valve and to the anus below. It is a tubular organ, coiled and folded. The main function of the large intestine is to transmit and transform waste. Transmission and transformation refer to the actions of conducting and changing. The large intestine receives the food residue passed down from the small intestine and absorbs excess water, forming feces, which are then excreted through the anus, hence the large intestine is known as the “transmission organ.” The large intestine’s transmission and transformation functions extend the stomach’s function of descent, and are closely related to the spleen’s upward transformation, the lungs’ dispersing function, and the kidneys’ qi transformation. If the large intestine’s transmission is impaired, it can lead to abnormal bowel movements, such as damp-heat in the large intestine, qi stagnation, resulting in abdominal pain and diarrhea, urgency, and blood in the stool; if the large intestine is filled with heat, the intestinal fluids may dry up, leading to constipation; if the large intestine is deficient and cold, it may lead to mixed food and water, causing bowel sounds and diarrhea.The BladderThe bladder is located in the lower abdomen, a hollow sac-like organ, with the ureters connecting it to the kidneys above and the urethra opening to the front. The main function of the bladder is to store and excrete urine. Urine is transformed from body fluids, and its formation relies on the kidneys’ qi transformation, which descends to the bladder and regulates its opening and closing, ultimately excreting it. Therefore, the bladder’s qi transformation function is based on the physiological foundation of the kidneys’ qi transformation. If the qi transformation functions of the kidneys and bladder are impaired, it can lead to urinary difficulties, such as frequent urination, urgency, painful urination, or incontinence.The San JiaoThe San Jiao refers to the upper, middle, and lower Jiao, and is one of the six Fu. Among the Zang and Fu organs, the San Jiao is the largest, having a name but no physical form, hence it is called the “lonely Fu.” In terms of location, the upper Jiao is above the diaphragm, including the heart and lungs; the middle Jiao is below the diaphragm and above the navel, including the liver, gallbladder, spleen, and stomach; the lower Jiao is below the navel, including the large and small intestines, bladder, and kidneys. The San Jiao is exteriorly connected to the pericardium.The specific functions of the San Jiao are:1. Governing all qi, presiding over the body’s qi transformation activities. The San Jiao is the pathway for the body’s original qi. The original qi originates from the kidneys and must pass through the San Jiao to be distributed throughout the body, stimulating and promoting the functional activities of all Zang and Fu organs, thus maintaining the normal life activities of the body. The original qi is the driving force for the transformation of qi, and the San Jiao’s passage of original qi is related to the normal functioning of the body’s qi transformation.2. Serving as the pathway for the movement of body fluids. This means the San Jiao has the role of unblocking the water pathways and facilitating the movement of body fluids. Although the metabolism of body fluids relies on the cooperation of various Zang and Fu organs, it must also depend on the smooth functioning of the San Jiao’s water pathways to proceed normally. If the San Jiao’s water pathways are obstructed, the functions of the lungs, spleen, and kidneys in regulating fluid metabolism will be difficult to perform. Therefore, the San Jiao plays an important role in fluid metabolism.The gallbladder is the official of justice, making decisions; the stomach is the official of storage, from which the five flavors emerge; the small intestine is the official of reception, from which transformations emerge; the large intestine is the official of transmission, from which changes emerge; the San Jiao is the official of drainage, from which the water pathways emerge; the bladder is the official of storage, where body fluids are kept.
The Theory of Generating Relationships Among the Five ElementsThe relationships among the five Zang organsThe generating relationships among the Five ElementsFor example, wood generates fire, meaning the liver (wood) nourishes the heart (fire); the liver stores blood, and the heart governs blood vessels. When the liver’s blood storage function is normal, it helps the heart’s function of governing blood vessels. Fire generates earth, meaning the heart (fire) warms the spleen (earth); the heart governs blood vessels and spirit, while the spleen governs transportation and blood production. When the heart’s function of governing blood vessels is normal, it can nourish the spleen; thus, the spleen can perform its functions of transportation, blood production, and blood governance. Earth generates metal, meaning the spleen (earth) assists the lungs (metal); the spleen can benefit qi, transform qi and blood, and transport essence to nourish the lungs, promoting the lungs’ function of governing qi. Metal generates water, meaning the lungs (metal) nourish the kidneys (water); the lungs govern clarity, while the kidneys govern essence storage. The lungs’ clear energy helps the kidneys store essence and govern water. Water generates wood, meaning the kidneys (water) nourish the liver (wood); the kidneys store essence, and the liver stores blood, allowing kidney essence to transform into liver blood, thus assisting the liver’s normal function. This mutual nourishing relationship among the five Zang organs is explained using the theory of generating relationships among the Five Elements.The Relationships Between the Zang Organs1. Heart and small intestine: The meridians are interconnected, and they are mutually related. If the heart’s heat is excessive, it can lead to mouth and tongue sores. If the heart’s heat transfers to the small intestine, symptoms such as short, red urine and painful urination may occur.2. Liver and gallbladder: The gallbladder is attached to the liver, and the Zang and Fu are interconnected, forming a mutual relationship. Bile originates from the liver, and if the liver’s smoothness is abnormal, it will affect the normal excretion of bile. Conversely, if bile excretion is abnormal, it will also affect the liver. Therefore, liver and gallbladder symptoms often occur simultaneously, such as jaundice, rib pain, bitterness in the mouth, and dizziness.3. Spleen and stomach: In terms of characteristics, the spleen prefers dryness and dislikes dampness, while the stomach prefers moisture and dislikes dryness; the spleen governs rising, while the stomach governs descending. In terms of physiological functions, the stomach is the sea of food and drink, governing digestion; the spleen governs the transportation of the stomach’s fluids. The two organs work together to complete the digestion, absorption, and transportation of food. If the spleen’s qi does not rise, the stomach’s qi will not descend, leading to symptoms such as poor appetite, nausea, abdominal distension, and constipation. If the diet is irregular, causing the stomach to lose its harmony and descent, it will affect the spleen’s upward transformation, leading to symptoms such as abdominal distension and diarrhea. Due to the close relationship between the spleen and stomach physiologically, they also influence each other pathologically, so they are often discussed together in clinical practice, and treatments often target both the spleen and stomach.4. Lungs and large intestine: The meridians are connected, and they are mutually related. If the lungs’ qi descends, the large intestine’s qi can flow smoothly, allowing it to perform its transmission function. Conversely, if the large intestine maintains its transmission, the lungs’ qi can descend. For example, if the lungs’ qi is stagnant and loses its descending function, it may lead to obstruction in the large intestine’s transmission, resulting in constipation. Conversely, if the large intestine’s transmission is obstructed, it can lead to abnormal lung function, causing shortness of breath and coughing. In treatment, if the lungs have excess heat, the large intestine can be purged to allow heat to be expelled from the large intestine. Conversely, if the large intestine is obstructed, it can help clear the lungs’ qi to facilitate the large intestine’s qi movement.5. Kidneys and bladder: The meridians are connected, and they are mutually related. Physiologically, one is a water organ, and the other is a water bowel, working together to maintain the balance of fluid metabolism (with the kidneys being the primary organ). Kidney yang transforms and allows water to descend into the bladder, which also relies on kidney yang to function and excrete urine. Pathologically, if kidney yang is insufficient, it can weaken bladder function, leading to frequent urination or incontinence; if damp-heat accumulates in the bladder, it can affect the kidneys, leading to symptoms such as low back pain and blood in the urine.6. Pericardium and San Jiao: The meridians are connected, and they are mutually related. For example, in clinical practice, when damp-heat combines with pathogens in febrile diseases, it can linger in the San Jiao, leading to symptoms such as chest tightness, heaviness, reduced urination, and loose stools, indicating a problem in the qi level. If this development is not stopped, the warm pathogen can enter the nutrient level from the qi level, penetrating the San Jiao and leading to symptoms such as coma and delirium.Practical SignificanceThe theory of the interrelationship between Zang and Fu has practical significance in acupuncture treatment. For example, asthma in the hand Taiyin lung meridian is often treated with the He Gu point of the hand Yangming meridian, while the stomach meridian of the foot Yangming is often treated with the Yin Ling Quan point of the foot Taiyin spleen meridian, achieving satisfactory results. These treatments are based on the theory of the interconnection of the Zang and Fu meridians.The spleen and stomach are the foundation of life.The human body is an organic whole composed of Zang and Fu organs, meridians, skin, muscles, tendons, bones, essence, qi, blood, and body fluids.The theory of Zang and Fu studies the physiological functions and pathological changes of the Zang and Fu organs and their interrelationships.The Zang organs include the heart, liver, spleen, lungs, and kidneys, known as the five Zang. Additionally, the pericardium is located around the heart, with connecting vessels, serving as a pathway for qi and blood and protecting the heart, thus it is also referred to as a Zang organ. The Fu organs include the gallbladder, stomach, small intestine, large intestine, bladder, and San Jiao, known as the six Fu.The Zang and Fu organs are the main organs for transforming essence, blood, and body fluids, promoting metabolism, and maintaining the body’s functional activities. Specifically, the five Zang are responsible for storing vital essence (which refers to essence, blood, and body fluids), while the six Fu are responsible for receiving, digesting, absorbing, transporting, and excreting food. Therefore, the Zang primarily focus on storage, while the Fu focus on movement.There is a mutual connection between the Zang and Fu, whether it is between Zang and Zang, Fu and Fu, or Zang and Fu. The five Zang are also closely related to the five body types and the five senses and seven orifices. The relationship between the five Zang and the five body types is: the heart governs the vessels, the liver governs the tendons, the spleen governs the muscles, the lungs govern the skin, and the kidneys govern the bones. The relationship between the five Zang and the five senses and seven orifices is that the heart opens to the tongue, the liver opens to the eyes, the spleen opens to the mouth, the lungs open to the nose, and the kidneys open to the ears and the two yin (the nose, eyes, and ears each have two, along with the front and back yin, making a total of nine orifices). Because the five Zang are related to the five body types and the five senses, changes in the five Zang often reflect in the corresponding body tissues and orifices.In TCM, the understanding of the functions and changes of the Zang and Fu is relatively rough due to historical limitations. The concept of Zang and Fu in TCM is not only an anatomical concept but more importantly, a physiological and pathological concept. Therefore, the concept of “Zang and Fu” in traditional Chinese medicine differs from the concept of “organs” in modern medicine. For example, the “heart” in TCM does not completely equate to the heart in modern medicine; it not only anatomically represents the heart but also physiologically includes the functions of some organs in the circulatory and nervous systems. When studying traditional Chinese medicine, we should adopt a dialectical materialist perspective, combine it with modern medicine, grasp its essence for analysis and research, eliminate the false and retain the true, and contribute to the creation of a unified new medicine in our country.Yin: San JiaoThe Zang and Fu are interconnected through the meridians and the flow of qi and blood, forming an organic whole. In a physiological state, they work both independently and cooperatively, constituting complex physiological activities. In a pathological state, they also influence each other. Therefore, their relationships can be reflected in physiological and pathological changes. Mastering these theories of Zang and Fu relationships has certain guiding significance for clinical differentiation and treatment.
The Zang and Fu and Body TissuesBody tissues mainly refer to vessels, tendons, muscles, skin, and bones. Their relationship with the five Zang is that the heart governs the vessels, the liver governs the tendons, the spleen governs the muscles (and limbs), the lungs govern the skin, and the kidneys govern the bones. At the same time, the abundance or deficiency of the body’s qi will also reflect in the most obvious areas. For example, if the heart is affected, the face may lose its color; if the liver is affected, the patient may experience cramps and thinning of the nails; if the spleen is affected, the muscles may waste away, and the lips may turn pale; if the lungs are affected, the skin may become dry; if the kidneys are affected, bone growth may be abnormal, and hair may become sparse. This all indicates that changes in the organs reflect in the corresponding body tissues.In TCM, how do the spleen and stomach relate to each other?In TCM, the human body is viewed as an organic whole, where the functions of various Zang and Fu organs, tissues, and organs are not isolated but are interconnected, forming part of the entire body’s activities. They communicate through the meridians, transmitting various information among the Zang and Fu organs, and in the context of qi, blood, and body fluids circulating throughout the body, they form a highly coordinated and unified whole.The spleen and stomach are interconnected through the meridians, forming a mutual relationship. The stomach governs reception, while the spleen governs transportation, working together to complete the digestion and absorption of food and the distribution of its essence to nourish the entire body, thus the spleen and stomach are both referred to as the “foundation of postnatal life.” The spleen governs rising, while the stomach governs descending; “the spleen should rise to be strong, and the stomach should descend to be harmonious.” The spleen prefers dryness and dislikes dampness, while the stomach prefers moisture and dislikes dryness; the two are opposites yet complementary, working together to complete the transformation of food. If the spleen’s qi does not rise, the stomach’s qi will not descend, leading to symptoms such as poor appetite, nausea, abdominal distension, and constipation; if the diet is irregular, causing the stomach to lose its harmony and descent, it will affect the spleen’s upward transformation, leading to symptoms such as abdominal distension and diarrhea.The relationship between the kidneys and the spleen and stomachIn TCM, the kidneys are regarded as the “source of innate essence,” while the spleen and stomach are the “source of postnatal essence,” thus the kidneys and spleen and stomach are mutually supportive and interdependent.If kidney yang is insufficient and cannot warm the spleen yang, symptoms such as abdominal cold pain, clear diarrhea, or early morning diarrhea and edema may occur; if spleen yang is deficient for a long time, it can lead to kidney yang deficiency, and when both spleen and kidney yang are deficient, it can lead to weak intestinal transmission, causing constipation, difficulty in excretion, cold pain in the abdomen, cold extremities, and low back pain.The liver’s regulation of fluid metabolismThe regulation of fluid metabolism is closely related to the liver. The liver governs smoothness and regulates qi movement, and the movement of water also relies on the promotion of qi. The liver regulates fluid metabolism mainly through three pathways: first, by regulating the qi movement of the San Jiao, ensuring the smooth flow of water pathways; second, by promoting the qi movements of the lungs, spleen, and kidneys, thus enabling them to perform their roles in fluid metabolism; third, when qi moves, blood moves, and when blood moves, water flows; thus, the smooth flow of qi and blood ensures the normal movement of fluids. If the liver is affected, smoothness is impaired, leading to qi and blood movement issues, resulting in stagnation of blood and water, causing fluid metabolism disorders. Clinically, symptoms such as edema and abdominal fluid accumulation may be observed.The spleen’s regulationThe spleen governs transportation and transformation, playing an important role in the body’s fluid metabolism.The meaning of transporting and transforming fluids is broad, including “the spleen disperses essence, which ascends to the lungs,” as well as the processes of transporting, distributing, and excreting fluids in various Zang and Fu organs. The spleen is located in the middle Jiao, serving as the hub for the rise and fall of qi and fluid metabolism. Fluids in the body descend from the lungs to the kidneys or ascend from the kidneys to the lungs, both relying on the spleen’s transportation function to maintain normalcy. When the spleen’s qi is sufficient, its function of transporting fluids is robust, allowing for coordinated and balanced fluid metabolism; conversely, if the spleen is deficient and fails to transport fluids, it will lead to internal stagnation of fluids, resulting in various diseases. Thus, as stated in 《素问·至真要大论》, “All dampness and swelling belong to the spleen,” emphasizing the spleen’s crucial role in fluid metabolism.The lungs’ regulationThe lungs govern dispersal, descending, and regulating the water pathways. Fluids have both clear and turbid components; the clear ones are distributed to nourish and moisten the organs, skin, and muscles through the lungs’ dispersing function, while the turbid ones are descended through the lungs’ descending function, passing through the San Jiao water pathways to the kidneys. Therefore, the lungs’ role in regulating fluid metabolism is primarily achieved through regulating sweating and the smooth functioning of the San Jiao water pathways, hence “the lungs are the upper source of water.” If the lungs are affected, fluid metabolism becomes abnormal, leading to symptoms such as edema and urinary difficulties.The San Jiao’s regulationThe San Jiao, as one of the six Fu, serves as the pathway for qi and fluid movement, playing an important role in the body’s fluid metabolism. As stated in 《素问·灵兰秘典论》, “The San Jiao is the official of drainage, from which the water pathways emerge.” This clearly explains the San Jiao’s function in fluid movement. Therefore, when the San Jiao is affected, it often impacts fluid metabolism. From clinical practice, diseases of the San Jiao often belong to excess conditions, commonly presenting with urinary retention and edema. When the San Jiao is obstructed, it can lead to systemic edema in the skin and muscles, as well as abdominal fluid accumulation and other symptoms.The small intestine’s regulationThe small intestine has the physiological function of separating the clear from the turbid, which is mainly reflected in three aspects: (1) Absorbing food essence; (2) Transmitting food residue to the large intestine; (3) Absorbing fluids to participate in fluid metabolism. While the small intestine absorbs food essence, it also absorbs some fluids, which descend to the bladder as urine, hence it is also referred to as “the small intestine governs fluids.” If the small intestine is affected, it may fail to distinguish between clear and turbid, leading to symptoms such as diarrhea and reduced urination.The Perspective of TCM on the Zang and FuAncient texts such as the “Nan Jing” have provided detailed discussions on the anatomy and physiological functions of the digestive system:The liver: The liver is located in the abdomen, beneath the diaphragm, and within the right rib. Its main physiological function is to regulate qi movement, meaning the rise and fall of qi. When the liver’s smoothness is normal, qi movement is smooth, qi and blood are harmonized, and the activities of the Zang and Fu organs are normal. If the liver’s smoothness is abnormal, it can lead to qi stagnation or excessive rising of liver yang, resulting in two types of diseases.The liver’s smoothness is a major link in the digestive system of the spleen and stomach, affecting the balance between the spleen’s upward transformation and the stomach’s downward transformation. The liver’s smoothness is an important condition for the normal functioning of the spleen and stomach’s digestive functions. The liver’s smoothness aids the spleen and stomach’s transportation and also assists in bile secretion and excretion. If the liver can smoothly regulate, bile can be secreted normally, aiding the digestion and absorption of the spleen and stomach; conversely, if the liver’s smoothness is impaired, it can lead to digestive dysfunction.Thus, the ancients said, “The food qi entering the stomach relies entirely on the liver’s smoothness to regulate, and the essence of food is transformed.”