Chapter 2 Getting Comfortable with the Skin You’re In

In This Chapter

Peeling back the layers

Finding ways to keep your skin in shape
Do you know what the biggest organ in your body is? It’s not
your brain, and it’s not your large intestine. Give up? The sub-
ject of this book may have given the answer away, so I’ll suspend
any further guesswork and tell you: It’s your skin. That’s right; your
skin is an organ (just like your heart, lungs, and liver). And if you
spread out the skin of the average adult it would measure 20
square feet, about the size of a twin-sized bed sheet!
In this chapter, I cover the ins and outs of your skin so that you
can see just where your acne originates. I acquaint you with the
many functions that your “largest organ” performs and tell you a
little about how to take care of it.
Exploring Your Largest Organ
You may not really think of the skin as an organ, like the heart and
lungs. To many people, skin seems more like a simple cover to pre-
vent their insides from falling out. An organ is a somewhat inde-
pendent part of the human body that performs a specific function.
Once you know that, you can see that the skin is an organ, because
it performs the following specific functions (in addition to others):
 Protects your body from infection
 Serves as a waterproof barrier between you and the outside
world
 Shields you from the sun’s harmful rays
 Provides cushioning like a shock absorber that defends you
from injury
 Insulates your body and keeps your temperature right around
a cozy 98.6 degrees Fahrenheit (37 degrees Celsius)
 Acts as an energy reserve
 Alerts you to potential harm through your sensations of touch
and pain
 Repairs itself (that’s why cuts heal)
 Produces vitamin D
Because your skin has so many functions, you may not be sur-
prised to discover that it also has a rather complicated structure
with many working parts. It contains hairs that have their own oil
glands and tiny muscles — I’ll bet that you didn’t know that hairs
have muscles! Your skin has sensory nerves — hot, cold, touch,
and pressure receptors. It also is home to blood vessels, lymph
vessels, and sweat glands. Plus, your skin has microscopic pigment-
producing cells, cells that work on your immunity, as well as cells
that protect and replace themselves. With all that going on, you
may be surprised that your skin doesn’t have its own zip code.
Human skin is made up of three layers. First come the top two
layers — the epidermis (the outside layer of skin that you can touch
and see) and the dermis (which is located directly beneath the epi-
dermis). Then comes the third, bottom fatty layer that the epidermis
and dermis rest upon, which is called the subcutaneous layer.
The prefix epi means “upon” and derm means “skin,” so, together,
they form epidermis (upon the skin). And obviously, dermis means
“skin.” The prefix sub means “under” and cutaneous is another ref-
erence to “skin,” so the word subcutaneous means “under the skin.”
(I guess they should have named it the “subdermis” if they wanted
to be totally consistent.)
In the sections that follow, I take you on a guided tour of each of
these layers. And like any good tour guide, I provide you with a
map in Figure 2-1.
Getting above it all: Hey, your
epidermis is showing!
Your epidermis is really strong. The majority of the cells that make
up the epidermis are called keratinocytes. Keratinocytes are filled
with an exceptionally tough, fibrous, protein known as keratin.
The Latin term for cells is “cytes.” Therefore, keratino-cytes, by defi-
nition, are cells (cytes) comprised of keratin.
Just as your skin has more then one layer (epidermis, dermis, and
subcutaneous layer), the epidermis itself has three layers. Within
these layers, there’s constant cellular motion going on.
 Outer layer: The outermost layer of the epidermis is known as
the stratum corneum, also known as the horny layer. This layer
provides your body with a durable overcoat that protects
deeper cells from damage, infection, and from drying out.
This layer of your skin is actually made up of dead skin cells.
(Your hair and nails are made of dead cells too!) So when
you look at your skin, you’re really seeing skin that is dead.
But these deceased skin cells only stick around for a little
while. Soon, they flake off — like when you wash, scratch
yourself, go shopping, sit in class, fall asleep, and even read
this book. Basically, all the time. In fact, every minute of the
day we lose about 30,000 to 40,000 dead skin cells off the sur-
face of our body.
 Middle layer: This layer is known as the stratum spinosum.
The cells in this layer looked kind of spiny to the scientists
who first described them.
 Inner layer: Known as the basal layer, the inner layer is like a
production facility for the new skin cells (keratinocytes) that
eventually make their way up through the stratum spinosum
to the outer stratum corneum to replace the dead older cells
you lose from the surface.
The keratinocytes in the basal layer stand up like little sol-
diers at attention on what’s called the basement membrane, a
barrier that separates the epidermis from the dermis; it’s the
anchor that joins the epidermis and dermis together. The ker-
atinocytes are kept alive by the underlying dermis — which
serves as their blood supply because the epidermis has no
blood supply of its own. But their upward journey carries
them farther away from their supply lines, and as they
approach the top, they begin to die. By the time they’ve
reached the outer layer of the epidermis, they’ve lost virtually
all of their cellular contents except for tough keratin fibers
and other solid proteins. Even as they dry up and die, they
become much more resilient and durable and become the flat-
tened cells that form the stratum corneum. This one-way trip
takes about two weeks to a month to accomplish. Figure 2-2
demonstrates the process.
When an injury or an acne pimple penetrates the basement
membrane, a scar may result. (I describe acne scarring in
Chapter 16.)