"The Skin as a City Wall: How Traditional Chinese Medicine Views Immunity"

caulocare
May 29
4 min read

By Dr. Phumlarp Caulo | Caulo Care, New York | May 29, 2025

In both Western anatomy and Traditional Chinese Medicine (TCM), the human skin serves not only as a physical barrier but also as a battlefield — the first frontier where our body defends itself against external threats. When viewed through the lens of TCM, the skin transforms into something far more poetic: a city wall guarded by the Lung Channel, its energetic generals, and a vigilant army of protective Qi.

🧬 Layers of the Human Skin: The Three Defense Zones

Modern biomedical science recognizes three primary layers of the skin:

1. Epidermis – The Outermost Wall

The epidermis, especially its outermost layer (stratum corneum), is the body’s first line of defense.
Functions:
- Prevents microbial invasion
- Minimizes water loss
- Shields against temperature fluctuations
In a TCM perspective, this outer shield is likened to the outer wall of a fortress, a barrier against "evil qi" (邪氣, Xie Qi), such as Wind, Cold, Dampness, and pathogenic microbes.

2. Dermis – The Strategic Core

Rich in blood vessels, nerve endings, sweat glands, and hair follicles.
Functions:
- Regulates temperature
- Transmits sensory signals
- Nourishes the epidermis
In TCM, this layer symbolizes the inner defense zone, where Wei Qi (衛氣) patrols and communicates, much like soldiers detecting and responding to enemy threats at the city wall.

3. Hypodermis (Subcutaneous Tissue) – The Supply Base

Composed of adipose tissue and connective tissues.
Functions:
- Stores energy
- Cushions the internal organs
- Maintains core temperature
In TCM, this layer resembles a military reserve base, where Qi (氣) and Blood (血, Xue) are stored, nourishing the body and skin from below.

🌬️ The Lung Channel: The Commander of the Defensive Wall

In Traditional Chinese Medicine, the Lung (肺, Fei) governs the skin and body hair (皮毛, Pi Mao). It distributes Wei Qi (defensive Qi) throughout the body, especially to the surface layer, serving as the commander of the border patrol.

1. The Lungs in TCM: An Organ of Defense and Regulation

Yin organ (Zang)
Generates Zong Qi (宗氣), the foundational Qi of breathing and heart function
Closely connected to the health and vibrancy of the skin
When the lungs are strong, the skin appears bright, supple, and resilient.
When weak, the skin may become dry, vulnerable, and more susceptible to infection.

2. Lung Meridian (手太陰肺經): The Path of Protection

Begins in the chest (lung area) and runs through the arm to the thumb.
Distributes Qi and Fluids (津液, Jin Ye) throughout the body, especially to the skin.
Primary Functions:
- Circulates Wei Qi to the surface
- Regulates the opening and closing of pores
- Deflects Xie Qi from penetrating through the skin

🛡️ Wei Qi (衛氣): The Invisible Army

Wei Qi — translated as Defensive Qi — acts as a mobile military unit patrolling the skin and outer defenses.

Origin:

Formed from Gu Qi (谷氣, food-derived Qi) and Qing Qi (清氣, air-derived Qi)
Processed by the Lungs, making them the supreme commander of this defensive force

Functions:

Blocks the invasion of environmental pathogens (風寒濕熱邪: Wind, Cold, Damp, Heat)
Regulates pore activity and thermoregulation
Adjusts to environmental shifts such as cold wind or intense heat

Dynamic Nature:

Daytime (Yang Time): Wei Qi patrols the epidermis, scanning for threats
Nighttime (Yin Time): Wei Qi retreats inward to the dermis and hypodermis, healing and regenerating the inner terrain

🏯 Symbolism: The Lung Channel as a Walled City

The metaphor of the Lung Channel as a “walled city” (城牆) offers a vivid understanding of holistic defense:

Skin = City Wall:
- First barrier against foreign invaders (Xie Qi)
- Its strength determines the body's resistance
Wei Qi = City Soldiers:
- Patrols the walls, fights off intrusion, regulates the gates (pores)
Lungs = General of the Army:
- Commands deployment, determines strength and agility of Wei Qi
- Weak lungs = weak command = compromised wall = increased disease risk

⚠️ When the Lung Qi is Weak: Vulnerability at the Gates

TCM identifies this condition as Fei Qi Xu (肺氣虛) – deficiency of Lung Qi:

Symptoms:
- Weak immune defense
- Dry or itchy skin
- Susceptibility to colds, flu, and allergies
- Easy sweating or chills

TCM Therapeutic Strategies:

Acupuncture points such as:
- LU7 (Lie Que 列缺): Boosts Wei Qi and regulates the exterior
- LU9 (Tai Yuan 太淵): Tonifies Lung Qi and strengthens the meridian
Herbal formulas featuring:
- Huang Qi (黃芪, Astragalus): Boosts immunity and Lung Qi
- Bai Zhu (白术): Strengthens spleen to support Wei Qi
Diet and lifestyle to nourish the lungs and build resilience

Conclusion: Are Your Walls Guarded Today?

In an era where invisible pathogens challenge our well-being daily — viruses, pollutants, climate extremes — understanding the walled city of the skin offers both a poetic and practical reminder: our immunity begins not only in our lungs and blood, but also in the silent patrol of Wei Qi, and in the unseen strategy led by the Lung Channel.

Dr. Phumlarp Caulo, Founder, Caulo Care Acupuncture WellnessNew York, May 29, 2025

This information is only educational and should not be construed as medical advice.

Everything must be balanced, and the suggestions may not apply to you.

A specialist doctor should be consulted for any medical advice or diagnosis.

BOOK AN APPOINTMENT NOW!

Acupuncture near me at Forest Hill, NY

🔶🔷🔶🔷🔶🔷🔶🔷🔶🔷🔶🔷

Dr. Phumlarp Caulo LA,c, MAc. OM, DAHM

Doctor of Acupuncture/Chinese Medicine

Caulo Care Acupuncture

🔖 By appointment only

📧 bookingcaulocare@gmail.com