Traditional Chinese Medicine's understanding of male Tian Gui (a concept in Traditional Chinese Medicine) and its regulation of the five internal organs and six bowels.

The male Tian Gui (天癸) is a substance that promotes male growth and development, reproductive function, sperm production, maintenance of secondary sexual characteristics, and fertility; it is not male semen. Tian Gui is developed during the embryonic period, stored in the kidneys, and is influenced by the strength of kidney qi and the nourishment from food and water. After the age of sixteen (around 18), Tian Gui is abundant, and semen overflows, initially establishing fertility; after the age of forty (around 40), Tian Gui declines, semen decreases, and fertility diminishes. Tian Gui exerts its physiological functions through the synergistic action of the heart, kidneys, other organs, meridians, and the flow of qi and blood. The production, maturation, depletion, and quantity of Tian Gui can be reflected in the body's physiological and pathological aspects, and can indicate the etiology and pathogenesis of certain diseases, thus guiding clinical treatment.

The generation and excretion of reproductive essence is a unique physiological characteristic of men. The generation of reproductive essence is based on the normal functioning and coordination of the internal organs, meridians, and qi and blood, with the strength of kidney qi and the depletion of tiankui (menstrual blood) as decisive factors. In other words, the amount of reproductive essence generated is directly controlled by kidney qi and tiankui. The heart governs the spirit, the kidneys store essence, the liver regulates the flow of qi, the spleen governs the control of qi, and the lungs govern the flow of qi in the body. The normal functioning and coordinated action of all these organs maintain the normal functioning of ejaculation. When the kidneys, as the saying goes, "are the palace of strength, from which skill arises," are functioning normally, and with sufficient quantity and quality of reproductive essence, a man possesses the ability to conceive.

In summary, the kidneys govern the body's growth, development, aging process, and reproductive activities. The natural rise and fall of a man's life is an external manifestation of the natural rise and fall of kidney qi. Traditional Chinese medicine also incisively reveals that the foundation of male sexual and reproductive abilities lies in three substances: kidney qi, Tian Gui (a concept in Traditional Chinese Medicine), and reproductive essence. These three substances are distinct yet closely interconnected. Tian Gui originates from innate essence and is nourished by acquired food and water; the abundance of kidney qi promotes the abundance of Tian Gui, and with the abundance of Tian Gui, the seminal vesicle produces mature sperm, resulting in semen ejaculation. Among the three, Tian Gui is the key substance promoting vigorous male sexual and reproductive abilities, and the strength of sexual and reproductive abilities changes with the rise and fall of Tian Gui. Therefore, male physiology is a dynamic process of normal and coordinated functional activity centered on the kidneys' role in reproduction, based on the three substances of kidney qi, Tian Gui, and essence, with kidney qi and Tian Gui-essence-as the main axis. This understanding in Traditional Chinese Medicine accurately reveals the mechanism and process of male sexual physiology, and Western andrology research on male sexual physiology yields similar results.

**Nourishing and replenishing the essence requires proper conditioning of the five internal organs.**

"Five internal organs and six bowels" is a term exclusive to men, because modern medical research shows that only men have five internal organs and six bowels, while women have six.

The Complete Works of Jingyue, Treatise on Treatment of Physical Form, states: "All blood is stored in the liver and transformed by the spleen and stomach, while essence is governed by the kidneys and received from the five viscera." Although the five viscera each have their own functions, such as the heart governing blood, the lungs governing qi, the liver storing blood, the spleen controlling blood, and the kidneys storing essence, the functions of each viscera are also interdependent, such as the mutual transformation of qi and essence, the mutual generation of qi and blood, and the common origin of essence and blood.

This shows that normal male physiological activities are also carried out through the combined action of the internal organs.

In Traditional Chinese Medicine (TCM) theory, the term "kidney" primarily refers to a functional system, rarely referring to a physical organ. This is also true in TCM andrology. In andrology, the function of the kidney generally refers to the functions of the urinary and reproductive systems and related systems. The male external genitalia and internal reproductive organs are directly connected to the kidney through meridians; the replenishment of Tian Gui (menstrual blood) and the generation and excretion of semen are closely related to the kidney. The kidney plays an irreplaceable role in male physiological activities.

The essence stored in the kidneys includes both prenatal and postnatal essence. Prenatal essence is inherited from the parents, while postnatal essence originates from the refined essence of food and water produced by the spleen. Essence transforms into Qi, and Qi generates essence. The essence and Qi within the kidneys contain primordial Yin and primordial Yang, namely kidney Yin and kidney Yang, which are the foundation for maintaining the Yin-Yang balance in the human body. Kidney Yang, also known as primordial Yang, true Yang, the true fire of the gate of life, and prenatal true fire, is the driving force of kidney physiological activities and the root of Yang Qi in the human body. It plays a warming role in all organs, limbs, and bones. All male reproductive and sexual physiological activities, including the growth, development, and maintenance of the functions of internal and external reproductive organs, require the nourishment of kidney Yang. Kidney Yin, also known as the Yin fluid of the kidneys, is the material basis of kidney physiological activities and the source of Yin fluid in the human body. It plays a nourishing role in all organs, limbs, and bones and is equally important for maintaining the reproductive physiological functions of male sexual organs.

Kidney Qi is based on Kidney Essence. When Kidney Essence is abundant, Kidney Qi is vigorous, and Yin and Yang are in balance; conversely, when Yang is excessive, Kidney Qi is deficient, leading to an imbalance of Yin and Yang. Kidney Essence, Kidney Qi, Kidney Yin, and Kidney Yang interact to maintain the normal physiological functions of the kidneys. The waxing and waning of Kidney Qi reflects the physiological process of male growth and development. A man's entire life-from growth and development to maturity and aging-is the entire process of the waxing and waning of Kidney Qi, and the internal waxing and waning of Kidney Qi can be manifested through the waxing and waning of external physiological characteristics.

The liver is the regulatory center for the storage and release of blood in the human body, and it also governs the moisturization of the fascia throughout the body. In andrology, the liver's relationship with male physiology is mainly reflected in its role in moisturizing the tendons and ligaments, coordinating semen excretion, and the mutual generation of sperm and blood.

The liver stores blood, meaning it regulates blood circulation, volume, and storage. The fascia (tendons) governed by the liver have broad and narrow interpretations. Broadly, they refer to the fascia of the body; narrowly, they specifically refer to the external genitalia, the reproductive organs located in front of the genitals, including the penis, scrotum, and testicles.

The external genitalia are nourished by liver blood and have a high demand for blood. During sexual activity, the liver can supply the external genitalia with enough blood in a timely and sufficient manner, so that the penis can suddenly become erect and remain firm to complete the entire sexual process. On the other hand, after sexual activity, the liver can promptly and quickly regulate the excess blood volume in the external genitalia so that the penis can relax and return to normal.

Under pathological conditions, such as insufficient liver blood or impaired liver function, the external genitalia may lack nourishment, leading to underdeveloped or atrophied reproductive organs. During sexual activity, insufficient blood supply to the external genitalia can cause erectile dysfunction. Conversely, after intercourse, the liver may fail to regulate excess blood flow to the external genitalia, resulting in abnormal erections. All conditions related to liver blood deficiency, liver qi deficiency, liver qi stagnation, or pathogenic factors such as cold or heat affecting the liver can cause andrological diseases.

The liver governs the free flow of Qi, not only facilitating the movement of Qi throughout the body and regulating emotional and mental activities, but also playing a crucial role in male sexual activity. Sexual activity, primarily based on the Tian Gui (a concept in Traditional Chinese Medicine), is governed by the mind and spirit, and is inextricably linked to the smooth flow of liver Qi. Liver Qi thrives on smooth, unobstructed flow and is most susceptible to stagnation. Only when liver Qi is flowing smoothly and the Qi mechanism is unobstructed can a person experience sexual desire and engage in sexual intercourse. If liver Qi is stagnant or flows in reverse, leading to dysfunction of the liver's free flow of Qi and impaired Qi circulation, sexual dysfunction will occur. Insufficient liver function and emotional distress often manifest as sexual inhibition, such as low libido, apathy, and impotence, with reduced or ceased sexual activity. Excessive liver function, with excessive liver fire, often manifests as hyperactivity, resulting in increased libido, sexual activity, premature ejaculation, and nocturnal emission.

During sexual activity, semen excretion is closely related to the liver's function of regulating the flow of Qi. The liver's role in semen excretion is achieved through the regulation of the opening and closing of the seminal vesicle by liver Qi. When liver Qi flows smoothly and freely, the seminal vesicle opens appropriately, and semen excretion is normal. If liver Qi is stagnant and its flow is insufficient, the seminal vesicle opens slowly or does not close properly, which can lead to delayed ejaculation or anejaculation. If liver fire is excessive and its flow is too strong, the seminal vesicle opens prematurely, which can lead to premature ejaculation.