II. Research on the Spleen

The spleen is the foundation of postnatal life, governing middle qi and overseeing transportation and transformation; it is the source of qi and blood production and, like the kidney, plays a crucial role in human growth, development, health, and aging. The theories and doctrines concerning the spleen are an important component of the fundamental theories of TCM. In recent years, researchers have employed experimental methods to study the essence of the spleen and have achieved promising preliminary results. The "spleen" in TCM encompasses the following three aspects:

1. The Spleen Governs Transportation and Transformation

The meaning of the spleen's governance of transportation and transformation in TCM is broadly related to modern medicine's digestive, absorptive, gastrointestinal motility, and metabolic systems.

(1) The Spleen and Digestion

When the spleen fails to properly transport and transform, digestion becomes impaired and appetite diminishes. Some studies have used salivary amylase activity as an indicator and found that in patients with spleen deficiency, salivary amylase activity significantly decreases under effective load (acid stimulation), whereas in healthy individuals it increases. Others have observed that gastric acid basal output (BAO) and peak acid output (PAO) in patients with stomach pain due to spleen deficiency are both markedly lower than in normal individuals. Additionally, measurements of pepsin activity in 24-hour urine samples from chronic gastritis patients exhibiting spleen deficiency symptoms show no significant difference compared with healthy individuals. The Beijing Institute of Traditional Chinese Medicine has measured amylase activity in the urine of patients with spleen deficiency and found it significantly lower than in healthy people, preliminarily indicating that pancreatic amylase secretion function is reduced in such patients. Furthermore, pancreatic function tests conducted on patients with spleen deficiency reveal decreased chymotrypsin secretion.

From these studies, it can be seen that whenever spleen qi is deficient and its ability to transport and transform is compromised, salivary amylase secretion, basal and peak gastric acid output, urinary amylase activity, pancreatic amylase secretion, and chymotrypsin function all fall below normal levels. This demonstrates that the so-called "loss of spleen's transport and transformation function" in TCM essentially involves a reduction in various digestive secretory functions.

(2) The Spleen and Absorption

In addition to reduced secretion of various digestive enzymes, the loss of the spleen's transport and transformation function also entails changes in gastrointestinal absorption. For instance, some domestic institutions use xylose excretion rate as an indicator to study small intestinal absorption in patients with spleen deficiency. The Beijing Institute of Traditional Chinese Medicine has found that children with rickets and those prone to respiratory diseases who exhibit spleen deficiency symptoms have lower xylose excretion rates than normal. After strengthening the spleen through treatment, as the spleen deficiency symptoms improve, the xylose excretion rate also returns to normal. Similar results were obtained when the same experiment was repeated on adults with spleen deficiency symptoms. Pathological observations of gastric tissue from patients who underwent partial gastrectomy for spleen deficiency revealed enhanced regeneration of gastric mucosal epithelial cells but impaired differentiation into mature cells. Moreover, pathological examinations of duodenal biopsy specimens from patients with chronic gastritis and peptic ulcers exhibiting spleen deficiency symptoms showed flattened mucosal villi, extensive damage, and sparse or shed microvilli.

(3) The Spleen and Gastrointestinal Motility

The loss of the spleen's transport and transformation function also manifests as altered gastrointestinal motility. Patients with spleen deficiency typically experience belching, acid regurgitation, abdominal distension, and loose stools. According to TCM, this is evidence of disharmony between the ascending and descending movements of the spleen and stomach—what is referred to as "disharmony in ascending and descending." X-ray barium meal examinations have shown that most patients with spleen deficiency exhibit reduced gastrointestinal peristalsis and prolonged gastric emptying time. Using surface gastric electrical wave measurements as an indicator, it has been found that patients with spleen deficiency display lower amplitude of surface gastric electrical waves, a phenomenon that is particularly evident both on an empty stomach and after eating. Following treatment to strengthen the spleen and replenish qi, these conditions quickly improve. Additionally, using 13I isotope tracing to observe gastrointestinal emptying function, it has been discovered that tumor patients with spleen deficiency exhibit significantly faster gastrointestinal emptying compared with non-spleen-deficient tumor patients and healthy individuals, and improvements can be achieved by taking spleen-strengthening and qi-replenishing medications.

(4) The Spleen and Metabolism

The loss of the spleen's transport and transformation function also includes disturbances in the metabolism of nutrients. It has been observed that patients with atrophic gastritis and superficial gastritis who exhibit spleen deficiency symptoms have lower serum isocitrate dehydrogenase activity than normal (P<0.01). After treatment with Xiangsha Liujunzi Tang, this activity increases, though the difference before and after treatment remains significant, the post-treatment level still does not reach normal. Similarly, these patients also exhibit lower serum lactate dehydrogenase activity than normal, which significantly increases after treatment with Xiangsha Liujunzi Tang. Furthermore, it has been noted that in patients with stomach pain due to spleen deficiency, the average number of subcellular mitochondria per unit area of gastric mucosa is markedly reduced, while the mitochondria themselves show swelling, membrane defects, and cristae breakage. Mitochondria are organelles responsible for cellular bio-oxidation of nutrients and contain the enzymes necessary for oxidation. Therefore, studying the morphology and function of cell mitochondria in patients with spleen deficiency is highly meaningful for exploring the essence of the spleen.

2. The Spleen Governs Middle Qi

Middle qi is the foundation of postnatal life and an important component of the body's vital energy. As TCM states: "Where evil gathers, qi must be deficient," and "If vital energy is present within, evil cannot invade." Thus, vital energy and middle qi to some extent encompass immune function, and TCM also holds the view that a strong spleen is resistant to pathogenic factors. Some researchers have divided internal medicine inpatients into two groups—those with spleen deficiency and those without—and used peripheral blood lymphocyte counts, PHA skin tests, total E rose formation cell ratios, and active E rose formation ratios as indicators. They found that patients with spleen deficiency exhibit a clear tendency toward weakened cellular immunity, with the degree of decline positively correlated with the severity of anemia and hypoproteinemia in these patients. Similar findings have been observed in patients with chronic bronchitis, peptic ulcers, chronic nonspecific colitis, and chronic hepatitis who also exhibit spleen deficiency symptoms. Some researchers have used square capillary electrophoresis to examine lymphocytes in patients with spleen deficiency and found that lymphocyte electrophoresis rates are significantly lower. The decline in lymphocyte electrophoresis capability indicates a corresponding decrease in lymphocyte electrophoretic vitality, which may be one of the reasons for the weakened immunity in patients with spleen deficiency. Others have studied the content of Siga in the saliva of patients with peptic ulcers and chronic colitis who exhibit spleen deficiency symptoms and found that the content increases in such patients, especially among those with dampness accompanying spleen deficiency. After treatment, as clinical conditions improve, the content gradually decreases. TCM believes that the appearance of syndromes is related to individual constitution, and HLA is an important immunogenetic marker of the human body closely associated with immune response and susceptibility to disease. Some researchers have conducted preliminary studies on the association between spleen deficiency syndrome and HLA and found a significant relationship between spleen deficiency syndrome and HLA-Bn, whereas no such relationship was observed in chronic gastritis, chronic nephritis, or peptic ulcers used for comparative observation. This suggests a clear correlation between the essence of spleen deficiency and immunogenetic factors.

3. Disharmony Between Liver and Stomach

TCM holds that there are two scenarios for disharmony between liver and stomach in terms of pathogenesis: one is liver wood overacting on earth, and the other is spleen earth offending wood. The former presents with pain in the liver region, bitter taste in the mouth, dry throat, irritability, and loss of appetite and fatigue, while the latter manifests as fullness and distension in the epigastrium, intestinal rumbling and diarrhea, nausea and vomiting, and pain radiating to both flanks. From a Western medical perspective, these two scenarios generally involve disorders of the gastrointestinal autonomic nervous system, with the former likely reflecting heightened sympathetic nervous tension and the latter indicating dominance of parasympathetic nervous function. In light of this, domestic scholars have attempted to demonstrate the relationship between liver-stomach disharmony and the autonomic nervous system through certain research designs. It is known that the synthesis and secretion of salivary amylase are controlled by the autonomic nervous system. Patients with liver-stomach disharmony typically exhibit symptoms of liver depression and spleen deficiency, and some researchers continue to conduct experiments using patients with spleen deficiency as subjects. They find that when patients with spleen deficiency are in a resting state, their salivary flow rate increases and enzyme activity is also high, suggesting that the parasympathetic nerves controlling the salivary glands are relatively hyperactive. However, upon acid stimulation, enzyme activity not only fails to increase but actually declines, and the increase in salivary flow rate is also less than in normal individuals. This indicates that although the parasympathetic nerves of patients with spleen deficiency are in a state of hyperactivity, their stress response capacity is lower than that of normal individuals. Using 13I isotope capsule oral tracing, it has been found that patients with spleen deficiency exhibit faster gastrointestinal emptying, which can be corrected by intramuscular injection of atropine, demonstrating that parasympathetic nervous tension increases during spleen deficiency. Research on the functional state of the sympathetic nerves in patients with spleen deficiency is still ongoing. Skin potential is a sensitive indicator of the central nervous system's sympathetic nerve function; patients with spleen deficiency exhibit significantly lower skin potential than normal individuals whether at rest or under cold stimulation, and skin potential rises markedly after treatment to strengthen the spleen and replenish qi. The VMA content in the urine of patients with spleen deficiency is significantly lower than in normal individuals, and skin electrical activity often correlates with VMA content. Reduced dopamine β-hydroxylase activity is also a characteristic of patients with spleen deficiency, which increases after treatment. From a molecular biological perspective, the reason why the autonomic nervous system can influence the organs it controls is mainly due to neurotransmitter release at autonomic nerve endings interacting with corresponding receptors on target cells, thereby altering intracellular cyclic nucleotide levels and affecting cellular functional activities. Domestic researchers have studied changes in cyclic nucleotide levels in the blood of patients with spleen deficiency (results are inconsistent), but preliminary findings suggest that plasma CAMP levels are low in patients with spleen deficiency, which helps explain the low sympathetic nerve function during spleen deficiency. Based on current research, although different regions employ different methods and indicators, and results are not entirely uniform, it can be tentatively concluded that during spleen deficiency, sympathetic nerve function is low while parasympathetic nerve function is elevated, and both sympathetic and parasympathetic nerves have reduced stress response capacity.

---

III. Research on the Liver

The liver is one of the five zang organs and is equally important as the spleen and kidneys. Ancient texts contain numerous discussions about the liver, broadly divided into two aspects: the liver belongs to wood, has a free and unobstructed nature, governs dispersal and drainage, and when stagnated, becomes diseased; if diseased, it attacks earth and transforms into fire. The liver's wood relies on kidney water for nourishment; if water fails to nourish wood, liver yang rises excessively, leading to wind generation.

1. Liver-Qi Stagnation

Under normal circumstances, the liver must possess a free and unobstructed nature, capable of dispersal and drainage. Once the liver loses this quality, liver qi stagnation occurs. This serves as the foundational basis for various liver disease syndromes, from which liver wood attacking earth, liver qi transforming into fire, and liver qi rising against the flow can develop. In light of this, in recent years, some researchers have conducted experimental studies on the essence of liver qi stagnation. Using multi-indicator synchronous detection, they found that the primary pathological basis of this syndrome is autonomic nervous system dysfunction, specifically a reduced cyclic nucleotide ratio (CAMP/CGMP), increased blood viscosity, and diminished small intestinal absorption function. Japanese researcher Matsumoto Katsuhiko believes that the liver is a complex organ that can be categorized as part of the autonomic nervous system, but is also connected to mental processes, the central nervous system, vascular motor centers, and cardiac function. The Hunan Medical University Institute of Integrated Traditional and Western Medicine believes that preliminary research currently shows a close connection between the essence of the liver in TCM and the nervous system, as well as neurohumoral regulatory factors. Therefore, research on the essence of the liver must be based on the theories that the liver governs dispersal and drainage and stores blood.

2. Liver-Yang Excess

According to traditional TCM theory, liver-yang excess is the reverse pathological change of liver-qi stagnation. The former represents having surplus resources but lacking substance, while the latter signifies having sufficient substance but failing to utilize it effectively. Domestic researchers have observed the autonomic nervous system function of patients with liver-yang excess, changes in plasma cyclic nucleotides, comparisons of intracellular nucleotide content in red blood cells, changes in plasma atrial natriuretic peptide, and alterations in trace elements throughout the blood—microscopic indicators that collectively suggest that the neural-humoral regulation in cases of liver-yang excess is extremely complex. First, this condition may primarily result from enhanced peripheral sympathetic-adrenal medulla function: ① Autonomic nervous system dysfunction, with sympathetic overactivity accounting for 69.8%; ② Urinary CA, NE, E, and TMN levels—reflecting peripheral sympathetic-adrenal medulla function—are all elevated; ③ Central NE metabolite urinary MHPG levels are reduced; ④ Plasma CAMP and CGMP levels rise, with CGMP increasing more prominently, resulting in a declining CAMP/CGMP ratio; ⑤ Plasma TXB₂ and 6K-PGF levels rise, along with increased ratios; ⑥ Intracellular ATP, ADP, and NADP levels in red blood cells increase. Currently, it is widely acknowledged that when the sympathetic nervous system is excited, NE release increases, activating β receptors on cell membranes and stimulating adenylate cyclase (CAMP-ase), thereby raising intracellular CAMP levels and plasma CAMP levels. Catecholamines can also bind to α receptors, enhancing guanylate cyclase (CGMP-ase) activity and causing CGMP levels to rise. Prostaglandins (PG) can activate CAMP-ase activity in many tissues, increasing CAMP concentration, while imbalances in TXB₂-6K-PGF₁₂ content may affect key links in nucleotide metabolism. CA promotes material metabolism and enhances energy mobilization. Enhanced energy metabolism may be an important manifestation of excessive sympathetic-adrenal medulla function.

IV. Research on the Heart

The heart is the master of the five zang organs. The "Plain Questions·Secret Classic of Spiritual Oracles" states: "The heart is the sovereign organ, where divine spirit originates." The "Spiritual Pivot·Questions About the Mouth" says: "The heart is the master of the five zang organs and six fu organs... When the heart beats, all five zang organs tremble." The "Spiritual Pivot·Years of Heaven" states: "What constitutes the divine... When divine spirit resides in the heart, soul and spirit are fully present, thus forming a human being." TCM believes that the heart's main functions can be summarized as two: first, being the master of the five zang organs and six fu organs; second, being the origin of divine spirit. In recent years, research on this aspect has been relatively limited, with more emphasis placed on referencing existing experimental evidence for explanation and illustration.

Foreign researchers have conducted systematic studies on the mechanism of action of placebos and found that placebos exhibit different effects depending on the language used for induction. In such cases, subcutaneous injection of atropine can increase secretions, while saline solution can activate adrenal cortical function. Placebos may also reduce serum lipoproteins and decrease peripheral eosinophil counts. These experiments demonstrate that cognitive and conscious activities dominated by the cerebral cortex can alter the normal functions of various organs in the body, causing abnormal reactions to drugs that would normally elicit standard responses. Thinking and consciousness fall under the TCM concept of "divine spirit," which is governed by the heart, thus confirming the significance of the TCM theory that the heart is the master of the five zang organs and six fu organs. The renowned Soviet physiologist Bekov and his colleagues believed that every organ and tissue in the human body contains countless interoceptors, which play an indispensable role in maintaining homeostasis—for example, muscle interoceptors are crucial for coordination during movement, while gastrointestinal interoceptors regulate digestive organ activity... All these interoceptors function through pathways involving sympathetic and parasympathetic nerves, under the control of the central nervous system. The central nervous system, in turn, falls under the TCM concept of the heart governing divine spirit. Extensive research has been conducted on the functions of the hypothalamus, brainstem, and autonomic nervous system; when the hypothalamus is stimulated, numerous functions of various organs undergo noticeable changes, such as body temperature, respiration, heartbeat, sleep, sugar and fat metabolism, endocrine function, and so on. It has now been proven that the anterior and medial parts of the hypothalamus—including the suprachiasmatic nucleus, preoptic area, and gray tubercle region—control parasympathetic nerve activity; stimulating these areas can enhance parasympathetic nerve activity, manifesting as slower heart rate, vasodilation, and increased smooth muscle tone. Conversely, the posterior and lateral parts of the hypothalamus control sympathetic nerve activity; stimulating these areas can boost sympathetic nerve activity, resulting in dilated pupils, piloerection, accelerated heartbeat, increased blood pressure, and deeper, faster breathing.

Modern psychology holds that emotions and feelings are forms of human response to real-life situations. When real life aligns with the body's own needs, emotions and feelings typically manifest as joy, satisfaction, and love; when real life does not meet the body's needs, dissatisfaction, pain, fear, hatred, and anger arise. The former are positive emotions and feelings, while the latter are negative. Positive emotions and feelings can enhance the functions of various organs, whereas negative ones can inhibit them. Therefore, people generally believe that mood (emotions and feelings) is an important factor influencing the normal functioning of various bodily systems. Mood can be regulated through personal cultivation and orientation, and the directional influence of the cerebral cortex thus extends to regulating various departments of the body. Both emotions and feelings (mood) and the regulation through cultivation and orientation fall under the TCM concept of the heart governing divine spirit, and their impact on various body departments is consistent with the idea that the heart is the master of the five zang organs and six fu organs.

In summary, most of the heart's functions in TCM fall under the scope of modern medical brain functions. However, considering the heart's role in governing blood circulation, it also shares characteristics with the modern heart. Domestic researchers have used CXZ-I type ultrasonic cardiovascular diagnostic equipment to conduct preliminary observations on the left ventricular systolic and diastolic functions of patients with heart qi deficiency, heart yin deficiency, and blood stasis in the left ventricle. The findings show that in cases of heart qi deficiency, the mean value of the mitral valve-to-interventricular septum distance (EPSS) increases, while the mitral valve amplitude (CHE), stroke volume (SV), average left ventricular posterior wall contraction speed (MPMVS), average left ventricular posterior wall relaxation speed (MPWVD), ventricular wall thickening rate (△T%), EF slope (MVV), and the total amplitude of left ventricular posterior wall motion during rapid filling phase (R) all decrease, as do the ratios of R to PWE and other eight indicators. In cases of heart yin deficiency, besides the increased EPSS mean value, the diastolic function indicator MVV mean value also decreases significantly. Compared with heart qi deficiency, heart yin deficiency shares the common feature of reduced EPSS mean value, but differs in that other indicators decrease in heart qi deficiency while remaining unchanged in heart yin deficiency, resulting in statistically significant differences between the two. In cases of blood stasis, the SV and MPWVD mean values decrease, CHE and △T% also decrease, the MVV and R/PWE mean values decrease, while the EPSS mean value increases. These findings indicate that there is a clear relationship between TCM heart qi deficiency, heart yin deficiency, and blood stasis in the left ventricle and the heart's systolic and diastolic functions, and at the same time reveal both the similarities and differences in the essential nature of these three conditions regarding heart function, providing a material basis for understanding the traditional pathogenesis of TCM heart qi deficiency, heart yin deficiency, and blood stasis in the left ventricle.

<!-- translated-chunk:9/53 -->

Domestic studies have also observed the cardiac systolic time interval (STI) in patients with coronary heart disease complicated by heart qi deficiency syndrome, finding that these patients exhibit prolonged electromechanical systolic time (QS2), shortened left ventricular ejection time (LVET), prolonged pre-ejection period (PEP), and an increased PEP/LVET ratio, suggesting a close relationship between heart qi deficiency and left ventricular function. Based on the PEP/LVET ratio—the most sensitive and reliable indicator of left ventricular function—they set the upper limit of normal at 0.37 as the cutoff value; any value exceeding this threshold is considered indicative of abnormal left ventricular function. Statistical results show that the abnormality rate in the heart qi deficiency group of coronary heart disease patients is 94.7%, while in the heart qi and yin deficiency group it is 91.7%; no abnormalities were found among other coronary heart disease patients.

In addition, some researchers used myocardial imaging to assess left ventricular function in patients with heart qi deficiency, confirming that these patients indeed have left ventricular dysfunction. Furthermore, another study examined the left ventricular systolic time interval in 95 patients classified according to different syndrome differentiation patterns, concluding that cardiac dysfunction, reduced cardiac output, and insufficient blood perfusion to systemic tissues are the pathological basis for the development of heart qi deficiency.

V. Research on the Lung

The lung is regarded as the "crown" of the five zang organs and six fu organs. According to traditional Chinese medicine, the lung governs qi, controls respiration, is associated with the skin and hair, and has a superficial–deep relationship with the large intestine. From this perspective, the lung in TCM not only encompasses the modern medical concept of the lung but also possesses functions that go beyond those of the modern lung. In addition to its respiratory function, the lung's role in governing qi, its association with the skin and hair, and its connection with the large intestine are all key components of the TCM organ theory. In recent years, some experimental studies have been conducted to explore the essence of these concepts; although the findings are still preliminary, they do indicate that the functional aspects of the lung in TCM do have a material basis.

1. The Lung and the Large Intestine: A Superficial–Deep Relationship

In recent years, domestic research on the superficial–deep relationship between the lung and the large intestine has consistently supported the notion that this traditional TCM theory has a material basis. First, it has been observed that severe intestinal dysfunction—such as various types of paralytic ileus, mechanical obstruction, and necrotizing enteritis—is often accompanied by respiratory failure. A classic example of concurrent intestinal and respiratory disorders is adult respiratory distress syndrome (ARDS). Modern medicine still struggles to provide a complete explanation for why severe intestinal diseases can lead to respiratory complications. However, from the perspective of traditional TCM, the consensus across classics such as the "Inner Canon," "Difficult Classics," "Treatise on Cold Damage," "Synopsis of Golden Chamber," and all subsequent medical works from the Tang and Song dynasties regarding the relationship between the lung and the large intestine seems entirely logical. Clinical practice guided by this principle has repeatedly proven effective. To further elucidate the underlying mechanism, some domestic researchers conducted a systematic study on 48 ARDS patients, finding that among these 48 cases, 25 had pre-existing intestinal dysfunction prior to the onset of ARDS, while 23 did not. By "intestinal dysfunction," we mean more than just ordinary gastrointestinal disturbances. Of the 25 cases, 21 were paralytic ileus, 3 were mechanical obstruction, and 1 was mesenteric artery embolism; among them, 16 developed secondary toxic shock. All 25 patients with severe intestinal dysfunction suddenly developed acute respiratory failure 1–3 days after the onset of intestinal symptoms, characterized by rapid breathing—often exceeding 28 breaths per minute—along with decreased arterial oxygen partial pressure (PaO₂ < 8 kPa), increased A-aDO₂ (greater than 4 kPa during spontaneous breathing and greater than 13.3 kPa during pure oxygen administration). These findings clearly demonstrate that severe intestinal dysfunction can lead to lung damage.

Building on these observations, some researchers created animal models by clamping the superior mesenteric artery to induce ischemic intestinal dysfunction. As a result, the lungs of the same animals exhibited grade II or higher lesions, whereas the lungs of unclamped animals showed no similar changes. At the same time, when equal numbers of animals were subjected to clamping of the renal artery or the lower limb arteries, no corresponding pulmonary changes were observed in the same individuals. Additionally, a comparative study was conducted between groups of animals where the superior mesenteric artery was clamped versus those where no arteries were clamped. The results showed that in the clamped group, endotoxin levels in the blood became positive after 90 minutes of clamping, while in the unclamped group, endotoxin levels remained negative even after 90 minutes of exposure to the superior mesenteric artery. These experiments confirm that intestinal dysfunction leads to lung pathology, thereby substantiating the material basis of the TCM theory of the lung and large intestine having a superficial–deep relationship. Preliminary evidence also suggests that this causal relationship may be linked to the production of endotoxins in the bloodstream.

Currently, in addition to the aforementioned experiments, some domestic researchers have induced lung lesions by creating permanent semi-ligation of the rectal ampulla. Others have improved upon these methods of clamping and permanent semi-ligation by using external ligation to create reversible narrowing of the distal rectum, which subsequently leads to a series of pathological changes in the lungs. The results indicate that this improved model essentially achieves the intended purpose—namely, the induction of a series of lung lesions. Beyond confirming the superficial–deep relationship between the lung and the large intestine, this model allows for the reversal of the narrowing through external intervention, restoring the animal to a normal state and thus enabling repeated use of the model. This provides better conditions for in-depth research into the essence of this theory. Under the conditions of this modified animal model, artificial formation of dry stool accumulation in the colon results in the appearance of Yangming腑实 syndrome in the animal model, which in turn can lead to specific lung lesions. These lesions include pulmonary congestion, pulmonary hemorrhage, and pulmonary necrosis. Electron microscopy reveals swelling and necrosis of the alveolar epithelium and macrophages, while other organs show no abnormalities. Experiments suggest that administering Dachengqi Tang to the model animals significantly alleviates the pulmonary symptoms.

2. The Lung Governs Qi

The significance of the TCM concept that the lung governs qi extends beyond its respiratory function to encompass other intrinsic functions of the lung itself; however, experimental research in this area remains relatively limited. According to a report from the Pulmonary Function Research Laboratory of Zhejiang Provincial Hospital of Traditional Chinese Medicine, they selected pulmonary function tests—direct indicators that best reflect the action of lung qi—and conducted observations and studies focusing on the lung's ventilation function. The results showed that in chronic obstructive pulmonary disease, patients with lung qi deficiency exhibited abnormal pulmonary function, whereas those without lung qi deficiency mostly had normal pulmonary function, with only a few showing mild abnormalities. Statistical analysis revealed significant differences between the two groups. Among the abnormal cases, most patients in the lung qi deficiency group suffered from moderate to severe ventilation impairment, and these impairments were predominantly mixed-type, significantly more pronounced than in the non-deficient group. Many current literature reports consider closed lung volume, flow–volume curves, and lung compliance to be highly sensitive indicators for early diagnosis of small airway diseases. In TCM clinical practice, however, early stages of such diseases often lack discernible syndromes, making the measurement of these indicators particularly important. These indicators increase in sensitivity in direct proportion to the degree of lung qi deficiency. The results obtained from 53 patients without lung qi deficiency in this study indicate that approximately half of them already exhibit microscopic changes indicative of lung qi imbalance. Therefore, it can be concluded that the TCM concepts of lung qi and the lung's governance of qi do have a material basis, despite the limited number of experimental studies conducted so far. As future research in this area deepens, the true nature of TCM's theory on the lung will inevitably be gradually revealed.

Section 5: Basic Principles of TCM Syndrome Differentiation and Treatment

Over nearly two millennia of development, traditional Chinese medicine has, through dialectical reasoning and syndrome-based etiology-seeking, established a series of fundamental principles for syndrome differentiation and treatment, including the Eight Principles, Zang-Fu differentiation, Six Meridians differentiation, Wei-Qi-Ying-Xue differentiation, Sanjiao differentiation, and Pathogenic Factor differentiation. These diagnostic frameworks serve as the main structure of TCM's clinical syndrome differentiation and treatment theory, giving TCM its distinctive characteristics. In the process of integrating traditional Chinese medicine with Western medicine and drawing on the strengths of both systems, it is essential to first emphasize the basic principles of TCM syndrome differentiation and treatment in order to fully leverage TCM's unique advantages, such as its macroscopic, holistic, and organism-response-oriented perspectives.

I. Eight Principles of Differentiation

The Eight Principles of Differentiation summarize clinical manifestations of disease into eight categories: Yin, Yang, Exterior, Interior, Cold, Heat, Deficiency, and Excess. It is the most fundamental principle of TCM differentiation and serves as the guiding framework for classifying TCM syndromes. When faced with a complex array of symptoms, the key lies in identifying the core elements and organizing them systematically to determine appropriate treatment methods and prescriptions—this can only be achieved by starting with the Eight Principles of Differentiation. According to TCM theory, any disease can be categorized under the Eight Principles: if the overall classification of the disease is not Yin, then it must be Yang; if the affected area is not on the surface, then it must be inside; if the nature of the disease is not Heat, then it must be Cold; and if the balance between pathogenic factors and vital energy is not Deficiency, then it must be Excess. Each of the Eight Principles has its own typical syndromes that can exist independently. At the same time, the four pairs of opposing syndromes within the Eight Principles exhibit an inseparable interrelationship. This "inseparable" quality means that there can be no Yin syndrome without a corresponding Yang syndrome, no exterior syndrome without an interior one, and the concept of Cold is defined precisely in opposition to Heat. Similarly, Deficiency and Excess are relative terms. Clinically, multiple syndromes often coexist, with overlapping attributes—for example, Fuzi Lizhong Tang syndrome, which manifests as interior Deficiency and Cold; Mahuang Tang syndrome, which manifests as exterior Cold and Excess; Guizhi Tang syndrome, which manifests as exterior Cold and Deficiency; and Chengqi Tang syndrome, which manifests as interior Excess and Heat. The complex and ever-changing progression of disease mechanisms—such as pathogenic factors moving from the exterior to the interior, then back to the exterior, alternating between Cold and Heat, and shifting between Deficiency and Excess—results in a wide variety of clinical presentations. Therefore, only by flexibly and skillfully applying the Eight Principles of Differentiation, accurately grasping the essence of the disease, and making a correct diagnosis, can we provide a reliable basis for treatment. Among the Eight Principles, the Yin and Yang categories are particularly important, as they serve as the overarching framework for the other six categories. Yin governs Interior, Deficiency, and Cold, while Yang governs Exterior, Excess, and Heat. Any clinical manifestation of disease is ultimately the result of an imbalance between Yin and Yang; only by grounding our diagnosis in these two principles can we gain a deeper understanding of Cold/Heat, Deficiency/Excess, and Exterior/Interior.