Why does skin become dry?

[Guest guest]

To those with questions about dry skin and improving skin care, I'm

beginning to wonder if it's not just about providing answers. From my

experience alone, I've answered this questions at least twice in the

past month, and a third time I referred to Dr. Sy's post explaining

the same thing written years before.

I'm wondering if self-education won't be more helpful to many here.

To those who are interested in learning more about your skin, I hope

the below sites and my comments will prove helpful.

Please, try very hard not to get discouraged -- it's not easy stuff,

even if you're comfortable with science, so if this is new to you, be

especially kind and patient with yourself. In my experience, spending

time with the basics always pays off down the road in fully

understanding -- and recognizing the cons of -- other material and

references, whether mainstream or alternative or whatever.

(1) To start, here's a group of microsopic slides and explanations of

the different layers of the skin:

http://www.meddean.luc.edu/lumen/MedEd/medicine/dermatology/melton/ski

nlsn/sknlsn.htm

Microscopic slides are stained with special dyes to bring out

different features of the tissues; the pink and blue are the dyes,

not the natural color of skin. These skin slides are sliced

perpendicular to the surface (at 90 degree angle, from the surface

down). If looking at sections is new to you, take a few minutes to

think about orientation -- it's not easy, but it's really important

to understanding the skin.

This site is confusing if you don't keep in mind that the outermost

epithelial layer (stratum corneum) -- the skin you can touch -- is

the top of your skin, and the deepest epithelial layer (stratum

germinativun) from which the keratinocyte (skin cell) derive, is

deepest. They mention the epithelial protective (waterproof) barrier,

but they don't mention specialized cells (melanocytes, Langerhans

cells, Merkel cells), which right now aren't important. Just keep in

mind that lots of stuff is happening in this layer.

Below the epidermis lies the two layers of the dermis: the blood

vessels and nerves (pappillary dermis) with the hair follicles and

glands below it (reticular dermis). Unfortunately, the skin appendage

slides aren't working, but they aren't important now. Just know

they're there, starting in the dermis and extending through the

epidemis to the outside.

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(2) After reviewing the above, you might want to take a look at

another site that goes into more detail. Starting at the third

paragraph, here's a narrative of the same anatomy:

http://www.dermatologychannel.net/skinanatomy/index.shtml

[For the truly obsessive-compulsive overachievers amongst us ,

here's a very tedious, poorly written, but an indepth narrative of

skin anatomy. If you do read it, skip the introduction and start at

Epidermis: http://www.emedicine.com/plastic/topic389.htm]

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(3) Once you have a feel for skin anatomy, take a look at this slide

presentation on Skin Physiology, Irritants, Dry Skin and

Moisturizers. This site is from Washington State's Dept of Labor and

Industries. The examples are for hands, but the same principles apply

to the face:

http://www.lni.wa.gov/sharp/derm/skinPhysiology/skinPhysiology_files/f

rame.htm

Some of the slides may be slow downloading for dial-up modems, but

hang in there. The diagrams are important but not to be taken

literally -- it's easy to understand it figuratively when the actual

layers are known. You can skip the slides of hand dermatitis and the

second and third contact dermatitis if you're on a dial-up

connection; the first allergic contact dermatitis slide is important.

Coreocytes = dead keratocytes, and the physical skin barrier =

natural skin barrier = epithelial protective barrier = waterproof

barrier. This site limits the barrier to just the stratrum corneum,

but I believe it begins deeper in the epidermis. Don't worry about

all the different details and components, just get the big picture:

as moisture decreases, healthy skin has its own protective measures

to increase moisture, which is part of the protective barrier. But in

the presence of irritants these protective measures break down, and

the skin becomes dry and scaly. (Those who advocate water only on

their face will discover why there are better options for healthy

skin care.)

Aside from all the problems of dry skin, a permeable barrier

increases the risk of absorption of sensitizing agents in products.

This is key: ingredients that do not cause problems with an intact

barrier may, in the face of a disrupted barrier, now cause a

dermatitis, worsening skin symptoms and further compromising the

epithelial protective barrier. Include active rosacea among the

active skin diseases that make one more suspectible to barrier damage.

The moisturizer section is not specific, but gives a sense of the

philosophy behind their function. Barrier repair moisturizers is a

misnomer -- the lipids in a moisturizer don't actually replace

missing skin lipids. The key point: a combination of lipid,

occlusive, and/or humectant agents help create a temporary barrier to

prevent water loss and protect against further damage to exposure to

environmental and other products. Moisturizers, when part of a skin

program that avoids new irritants, allows time for the protective

barrier to heal itself.

Again, this is not easy stuff, but I'm beginning to wonder if

reviewing and thinking about all this is a good first step to

understanding how to help your skin. It's only a first step, there's

a *huge* amount of information to understand about the skin, and

bring it all together.

I'll keep looking for better online educational tools. I was

surprised how much inaccurate stuff is on the Web, esp the patient ed

material (not only inappropriated watered down, but factually

incorrect). At least the above sites, as imperfect as they are,

relate fairly accurate information, as I understand it.

Hope this helps.

Marjorie

Marjorie Lazoff, MD