“I’m glad you asked,” he said. “Most of the time we only get bothered when something goes wrong.” He provided me with a mini-lecture about what lies beneath the city surface and how many things must be maintained in order to keep our rising demands for service satisfied.
Underneath our homes, sidewalks, and streets is a rapidly increasing mass of cables, pipes, and devices for the delivery and removal of water, electricity, data, natural gas, and sewage. Most of us have experienced the frustration of having a single one of these malfunction, as when a water line explodes or a utility line is cut.
Likewise, underneath the skin is a complex, intense system—one that outperforms any municipal system. Just as construction workers check and mark carefully before drilling, all of us who penetrate the body’s top surface must respect the boundaries of key structures and evaluate the anatomy prior to any invasive procedure. When treating people, we must consider a plethora of factors in order to provide comprehensive care, including personal and family history of disease; current medication use; social history including smoking, alcohol, and education; and the ability to pay for treatment.
The skin is a marvel. In the best circumstances, it heals itself, repairing and restoring its former integrity. It is grim in sorrow, radiates warmth in love, and shines in tranquility. The skin is an organ in and of itself, with its own personality, temperament, and particular eccentricities.
From a very early age, we use one sense the most—touch. When we reach out and touch an object that is too hot, an almost instantaneous event occurs. The temperature sensors in our skin send nerve signals running up the arm to the spinal cord and into the brain at over two hundred miles per hour. The brain interprets the sensation as pain and signals the hand muscles to move away, all before we can think.
Ashley Montagu in his book Touching: The Human Significance of the Skin focuses on what he calls the somatopsychic or centripetal approach, the manner in which tactile experience or its lack affects the development of behavior and “the mind of the skin.” He writes, “The skin, the flexible, continuous caparison of our bodies, like a cloak covers us all over. It is the oldest and the most sensitive of our organs, our first medium of communication, and our most efficient protector.”
The scale of these contributions is staggering. In a piece of skin the size of a quarter, more than three million cells, one hundred to three hundred sweat glands, fifty nerve endings, and three feet of blood vessels are at work. The skin comprises millions of cells of different kinds, some 350 different varieties per square centimeter. Huge numbers of touch, pressure, pain, heat, and cold sensory receptors live on the skin surface, particularly in the hands, face, and mouth. That’s why babies like to explore with their tongues: the tongue alone has more than nine thousand sensory receptors.
Montagu writes, “As the most ancient and largest sense organ of the body, the skin enables the organism to learn about its environment. It is the medium, in all its differentiated parts, by which the external world is perceived.”
The perception of the skin varies with each culture and time. The skin is considered a mirror of inner wellness in traditional Chinese medicine. In Greek mythology, the skin is a vulnerable shield. The modern, Western view increasingly recognizes skin as a permeable system, and recent research confirms that it has its own built-in, autonomous immune defenses.
We interpret skin as providing evidence for deeper problems, both bodily and psychologically. Our skin can torture us by disfiguring our bodies, but it also makes up the most basic facets of our social worlds. Without “normal” skin, we may find it hard to hold a job, feel self-esteem, make friends, or find love.
As Montagu writes, “On our skin, as on a screen, the gamut of life’s experiences is projected: emotions surge, sorrows penetrate, and beauty finds its depth. Soft, smooth source of youth’s vanity, skin later bears wrinkled witness to the toll of years. Radiant in health, it tingles to the affectionate touch.”
If I took all the patients I have seen and put them along an elastic spectrum, I could not stretch it far enough to encompass the contrasts in characters and skin that I have encountered. The differences within this multitude of humanity are as bright as the sunniest day and as dim as the prospects of a few of them rising above the genetic lottery.
During any given week I may see and treat a coal-black Nigerian boy who has barely learned to speak a bit of English; an old, world-worn Southern farmer with tiny islands of coral blue eyes in a sea of sun-damaged skin; a shoulder-stooped, bronzed Cuban man formerly a prisoner under Castro, his face sagging in depression and haunting memories; a homeless skinny black man, washing his feet in the exam room sink, specks of vitiligo everywhere on his skin, as if a dripping paintbrush had splashed randomly onto him; a red-armed backwoods white boy from Arcadia, dragged in by his sleepless mother because his skin has peeled off from eczema and he has missed most of the school year and scratched and hollered every night; a thin, slack-jawed, coffee-colored Haitian woman who arrived in Florida by boat in the middle of the night; and any number of those whose skin cancer or psoriasis or itching has gotten so out of control that they grab onto my office exam table like a buoy in the Atlantic during a hurricane and will not leave until they finally gain relief. In between may be visits with children who have warts or young men and women with acne, who recognize the relatively benign nature of their problems, and may even add some hope or levity to the day.
CHAPTER ONE
WHAT COVERS US?
The finest clothing made is a person’s own skin, but, of course, society demands something more than this.
—Mark Twain
Our skin, at the most basic level, defines us.
The skin is the body’s largest organ, averaging twenty square feet and nine pounds; it makes up 16 percent of the body’s weight. The skin is complicated but amazing in structure; it can be the target and dwelling place of thousands of tiny viruses, bacteria, or yeasts, yet does a stellar job of living with the good and keeping out the bad, all to protect the inner environment.
EPIDERMIS, DERMIS, SUBCUTIS: A TOUR OF THE SKIN
The epidermis, the outermost layer of skin, is a major part of the immune system. It is filled with Langerhans cells that form a first line of defense against environmental threats, identifying foreign materials and dangerous substances and ridding us of them. The epidermis is also part chemical plant, synthesizing vitamin D in the presence of sunlight, transforming a variety of helpful chemical compounds that interact with it, and inactivating substances that could be dangerous for us to absorb.
The epidermis protects the body from all kinds of insults. As Arthur and Loretta Balin write, “It seems fitting that the organ that defines the boundary between outside and inside worlds would be involved in the essential immune-system task of distinguishing between self and other.” Poison ivy is a common example: it is known to affect over 350,000 people in the United States annually, and demonstrates the wide range of possible sensitivities and reactions to exposure. Here’s how the reaction to poison ivy works. Urushiol is a chemical within the sap of the poison ivy plant that binds to the skin on contact. Urushiol shimmies its way into the skin and is broken down by T lymphocytes (or T-cells) that recognize it as a foreign substance, or antigen. The T-cells send out inflammatory signals called cytokines and the immune system pumps up the volume and calls in the troops—white blood cells. Still under the command of cytokines, the white blood cells turn into macrophages (super Pac Men) that eat up the foreign urushiol but also cause collateral damage to the normal tissue skin, resulting in inflammation and a dermatitis. A severe allergic reaction and blistering and oozing may occur in susceptible individuals; the fluid is produced by the body as blood vessels develop gaps and leak fluid through the skin. Approximately a quarter of the people exposed to poison ivy have no allergic reaction, while in extreme cases a anaphylactic reaction can occur. With age and repeated exposure, the sensitivity usually decreases.
The