From the perspective of modern medicine, the concept of body fluids is deeply connected to our body's mechanisms of fluid metabolism and maintaining homeostasis. A dry indoor environment is a primary cause accelerating our body's fluid loss. The skin is our body's largest organ and primary defense barrier against the external environment, and prolonged exposure to dry air weakens epidermal barrier function. As lipids in the skin stratum corneum and natural moisturizing factor are compromised, the skin can no longer prevent internal moisture from evaporating. This induces xerosis cutis and can trigger pruritus, keratin flakes, and in severe cases, inflammation.
Furthermore, dry air entering through the respiratory system dries the mucosa. The mucosa of the nose and throat plays an essential role in filtering fine dust, bacteria, and viruses, as well as regulating humidity, but when the mucosa becomes dry, this protective function declines. This leaves one vulnerable to infection and can cause chronic thirst, sore throat, and even nosebleeds. The eyes are no different. Tears play an important role in protecting and nourishing the eyes, but in a dry environment, the tear film becomes unstable and tears evaporate rapidly. Consequently, dry eye syndrome is aggravated, manifesting symptoms such as ocular fatigue, foreign body sensation, and hyperemia.
Interestingly, these external environmental factors also affect the autonomic nervous system. A dry, stifling environment unconsciously induces stress in our body, which can activate the sympathetic nerve. Excessive hyperactivity of the sympathetic nerve causes blood vessels to constrict and can lead to hypofunction of secretory glands, including the salivary glands and lacrimal glands. This further worsens xerostomia or dry eye and can bring about a systemic fluid metabolism imbalance.
Moreover, chronic dryness can affect the immune response. Weakened barrier function of the mucosa makes penetration by pathogenic bacteria easier, placing a burden on the overall immune system. Our body's cells perform optimally in an adequate fluid environment, and when the balance of body fluids—namely intracellular and extracellular fluids—is disrupted, it leads to cellular hypofunction, presenting as systemic symptoms like fatigue, impaired concentration, and lethargy. Ultimately, what Donguibogam refers to as body fluids can be interpreted in modern medicine as bodily fluids, intracellular and extracellular fluids, and the complex interactions of the nervous system and endocrine system that regulate them, while environmental dryness serves as a powerful factor breaking this delicate balance. Maintaining moisture in our body is not merely a skin issue, but a critical matter directly tied to overall health.
