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The Six Fu Organs in Traditional Chinese Medicine – The Stomach
The stomach is the organ that holds food in the abdominal cavity. Its shape is curved, connecting above to the esophagus and below to the small intestine. It is responsible for receiving and digesting food and is considered the warehouse for the essence of food and the sea of qi and blood. The stomach operates in a descending manner and is closely related to the spleen, which is often referred to together as the foundation of postnatal life. The stomach and spleen coexist in the central earth, but the stomach is classified as dry earth (yang), while the spleen is classified as damp earth (yin).
(1) Anatomy of the Stomach: 1. Location: The stomach is located below the diaphragm in the upper abdominal cavity, connecting above to the esophagus and below to the small intestine. The cavity of the stomach is called the “stomach cavity” and is divided into three parts: the upper part is called the “upper cavity,” which includes the cardia; the lower part is called the “lower cavity,” which includes the pylorus; the area between the upper and lower cavities is called the “middle cavity.” The cardia connects to the esophagus, and the pylorus connects to the small intestine, serving as the passage for food entering and exiting the stomach. 2. Structure: The stomach has a curved shape with a greater curvature and a lesser curvature. It is described as “curved, receiving food and water, with a shape that has a greater and lesser curvature,” and “the stomach is curved and bent.”
(2) Physiological Functions of the Stomach: 1. The stomach is responsible for receiving food and water: “Receiving” means accepting and containing. The stomach’s function of receiving refers to its role in accepting and containing food. Food enters through the mouth, passes through the esophagus, and is temporarily stored in the stomach; this process is called receiving, hence the stomach is referred to as the “great warehouse” and “sea of food and water.” “What a person receives in terms of qi is food, and what is stored is the stomach. The stomach is the sea of food and water.” “The stomach governs receiving, thus it is the storehouse of the five grains.” The physiological activities of the body and the transformation of qi, blood, and fluids depend on the nutrition from food, which is why the stomach is also called the sea of food, qi, and blood. The stomach’s function of receiving is the foundation for its function of digestion, and if the stomach is diseased, it will affect its ability to receive, leading to symptoms such as poor appetite, aversion to food, and distension in the stomach area. The strength of the stomach’s receiving function depends on the state of stomach qi, which is reflected in the ability to eat or not. If one can eat, the stomach’s receiving function is strong; if one cannot eat, the stomach’s receiving function is weak.
2. The stomach is responsible for digesting food: Digestion refers to the initial breakdown of food in the stomach, forming chyme. The stomach’s function of digestion means it transforms food into chyme. “The middle jiao is in the stomach cavity, neither rising nor falling, and is responsible for digesting food and water.” The stomach receives food from the mouth and allows it to stay briefly for initial digestion, relying on its digestive function to transform food into chyme. After initial digestion, the refined substances are transported by the spleen to nourish the body, while undigested chyme moves down to the small intestine, continuously renewing the digestive process. If the stomach’s digestive function is weak, symptoms such as stomach pain and regurgitation of undigested food may occur.
The functions of receiving and digesting food must work in conjunction with the spleen’s transportation function to be successful. Therefore, it is said: “The spleen is the earth. The spleen assists the stomach in digesting food; if the spleen qi does not circulate, the food in the stomach cannot be processed” (from the “Commentary on Treatise on Cold Damage”). The spleen and stomach work closely together: “The stomach governs receiving, and the spleen governs transportation; one receives and one transports,” allowing food to be transformed into essence, generating qi, blood, and fluids to nourish the entire body. Thus, the spleen and stomach are referred to as the foundation of postnatal life and the source of qi and blood transformation. The nutrition from food and the digestive function of the spleen and stomach are crucial for human life and health. Therefore, it is said: “Humans rely on food and water for life; without food and water, one dies.”
Traditional Chinese Medicine places great importance on “stomach qi,” believing that “humans rely on stomach qi for life.” When stomach qi is strong, all organs thrive; when stomach qi is weak, all organs decline. With stomach qi, there is life; without stomach qi, there is death. The term stomach qi has three meanings: first, it refers to the physiological functions and characteristics of the stomach. The stomach is the sea of food and water, with the functions of receiving and digesting food, as well as descending and passing through. These functions and characteristics are collectively referred to as stomach qi. Since stomach qi affects the function of the entire digestive system, it is directly related to the source of nutrition for the body. Therefore, the presence or absence of stomach qi is related to the life activities and survival of the human body, making it extremely significant in life activities. Thus, in clinical treatment, it is essential to protect stomach qi.
Second, it refers to the reflection of spleen and stomach function in the pulse, where the pulse appears calm and moderate. Because the spleen and stomach play an important role in digesting food and absorbing the essence of food to nourish the body, and this essence is transported through the meridians, the presence or absence of stomach qi can be reflected in the pulse. Clinically, the pulse of stomach qi is characterized by being calm and strong, neither too fast nor too slow. Third, it generally refers to the body’s vital energy. “Stomach qi is the qi of food, the qi of nourishment, the qi of movement, the vital qi, the clear qi, the defensive qi, and the yang qi.”
Stomach qi can be reflected in appetite, tongue coating, pulse, and complexion. Generally, normal appetite, normal tongue coating, a rosy complexion, and a calm and moderate pulse indicate the presence of stomach qi. Clinically, the presence or absence of stomach qi is often used as an important basis for judging prognosis; if there is stomach qi, there is life; if there is no stomach qi, there is death. Protecting stomach qi essentially means protecting the function of the spleen and stomach. When prescribing in clinical practice, it is crucial to remember “do not harm stomach qi”; otherwise, if stomach qi fails, all treatments will be ineffective.
(3) Physiological Characteristics of the Stomach: 1. The stomach governs downward movement: The stomach’s function of downward movement is in contrast to the spleen’s function of upward movement. The stomach’s downward movement refers to the characteristic of the stomach’s qi mechanism being smooth and descending. “All food and water that are digested in the stomach must pass from the stomach’s lower opening into the upper opening of the small intestine.” After food enters the stomach and undergoes initial digestion, it must descend into the small intestine, where it is further separated into clear and turbid substances; the turbid substances then move down to the large intestine and are eventually excreted as feces, thus ensuring the dynamic balance of the stomach and intestines. This is accomplished through the smooth downward action of stomach qi.
2. Preference for moisture and aversion to dryness: This refers to the stomach’s preference for moisture and aversion to dryness. As the stomach is yang earth, it prefers moisture and dislikes dryness, making it susceptible to dryness-heat conditions, which can easily damage stomach yin. Therefore, when treating stomach diseases, it is important to protect stomach yin; even when using bitter cold purgatives, they should be stopped once the condition is alleviated to avoid excessive cold harming yin.
In summary, the stomach’s preference for moisture and aversion to dryness is mainly reflected in two aspects: first, “the stomach is a yang organ that harmonizes with yin essence, and yin essence must descend.” The downward movement of stomach qi relies on the nourishment of stomach yin; second, the stomach’s preference for moisture and aversion to dryness is balanced by the spleen’s preference for dryness and aversion to dampness, ensuring the dynamic balance of the spleen’s upward movement and the stomach’s downward movement.
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