Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey Brainstuff. Lauren
Speaker 1: Bobelbam here. If you've ever watched a medieval era drama
Speaker 1: or fantasy, you may have marveled at the elaborate armor
Speaker 1: that characters wear into battle. Made of plates or scales
Speaker 1: or mail, armor is built to protect the wearer from
Speaker 1: specific types of weapons and attacks. It may not feel
Speaker 1: like it, but your skin is also a type of
Speaker 1: incredibly effective armor built to fend off specific attacks. It's
Speaker 1: not great at handling swords or arrows, but to be fair,
Speaker 1: those are relatively new inventions, far older threats like microbes
Speaker 1: and ultraviolet light. That's where our skin is a hero.
Speaker 1: It's our first line of defense as we move through
Speaker 1: the world, though it operates more like the manned walls
Speaker 1: of a castle than armor on a knight. Specialized cells
Speaker 1: and surrounding structures form a physical barrier between you and
Speaker 1: everything that's not you, sort of like a castle wall,
Speaker 1: and inside of that, an immune barrier stands at the
Speaker 1: ready like a castle's guard, to eliminate any threats that
Speaker 1: do make it through. But for our body's most visible organ.
Speaker 1: All of this happens on a microscopic level. So today
Speaker 1: let's delve into the skin barrier, how it protects us,
Speaker 1: and what can happen when something goes wrong. We've talked
Speaker 1: before on the show about the layers of the skin.
Speaker 1: The innermost layer, the hypodermis, provides structural support. It contains
Speaker 1: fat to insulate and cushion our underlying muscles and organs,
Speaker 1: plus blood vessels to get supplies to the middle layer,
Speaker 1: the dermis. The dermis contains all of the skin's equipment,
Speaker 1: nerve endings, sweat glands, pair follicles, and so on. All
Speaker 1: of that is sealed in and protected the outermost layer,
Speaker 1: the epidermis. The epidermis itself has two main layers, the
Speaker 1: inner of which is living, and the outer of which
Speaker 1: is dead. The dead skin cells of the outer layer
Speaker 1: are what we see and touch, and it's called the
Speaker 1: stratum cornium. The stratum corneum is often described as being
Speaker 1: like a brick wall, though luckily for us, a very
Speaker 1: flexible one, because it's made up of tough cells that
Speaker 1: are stacked and bound together with a kind of mortar
Speaker 1: of waxy, fatty lipids and some adhesive proteins. Those tough
Speaker 1: cells are called corneocytes. It's weird to think that their
Speaker 1: entire purpose in life is to die, but it's for
Speaker 1: the greater good of the organism. Because they're dead, they
Speaker 1: can't be infected by a virus or stopped from doing
Speaker 1: their job by bacteria. At their job is to sit there.
Speaker 1: They develop in the inner part of the epidermis, and
Speaker 1: as they're pushed to the out side, they die and
Speaker 1: flatten into sort of long, hardened envelopes containing keratin. Keratin
Speaker 1: is the protein that makes our hair and nails tough,
Speaker 1: and other things too, like feathers, hoofs, and horns. The
Speaker 1: etymology of the words keratin and corneocyte is actually related
Speaker 1: to the word horn. They all root back to early
Speaker 1: Indo European words for the hard and bony things that
Speaker 1: come off of an animal's skull. It's the same root
Speaker 1: where we get the word for the horn shaped cornucopia. Anyway,
Speaker 1: the tough corneocytes in your stratum corneum also contains stuff
Speaker 1: that can grab up molecules of water, which is good
Speaker 1: because ideally your outer skin should be dry. No one
Speaker 1: wants permanently moist skin, but not too dry. Having a
Speaker 1: bit of water in your skin keeps it pliable and
Speaker 1: prevents the skin from cracking. And as I said, the
Speaker 1: corneocytes are bound together with the sort of mortar made
Speaker 1: up of sticky proteins and a bunch of lipids, which
Speaker 1: are fatty or waxy substances. This is great because a
Speaker 1: it holds the corneosytes tightly in place, and also b
Speaker 1: it's what makes our skin more or less waterproof. Oil
Speaker 1: and water repel each other, so the oily lipids help
Speaker 1: make our skin impermeable to water. The stratum cornium is
Speaker 1: essentially the reason that all of the water that makes
Speaker 1: up some sixty percent of our body and makes our
Speaker 1: organs work stays in our body and doesn't just evaporate out.
Speaker 1: It also prevents many potentially harmful water based liquids, including
Speaker 1: ones that contain germs, from leaking into our body. Not
Speaker 1: too shabby for a stack of dead cells only some
Speaker 1: ten to twenty micrometers thick, which is about the thickness
Speaker 1: of one or two layers of plastic wrap. Even the
Speaker 1: fact that the corneocytes are dead and thus can't be
Speaker 1: repaired when they wear out and therefore get sloughed off
Speaker 1: and replaced on a continual basis. That's a feature, not
Speaker 1: a bug. This way, any microbes that might take up
Speaker 1: residents in or around your corneocytes get slothed right off
Speaker 1: with them. In healthy skin, your stratum cornium totally replaces
Speaker 1: itself about once a month. The cells in the layer
Speaker 1: of the epidermis directly beneath the stratum cornium where the
Speaker 1: corneocytes develop, are also tightly junctured together, adding to the
Speaker 1: security of the physical barrier of our skin. Plus they
Speaker 1: release some helpfully antimicrobial molecules. Because as impressive as this
Speaker 1: physical barrier is, it is then and delicate and pretty
Speaker 1: easily scratched or pierced. That's why we have an immune
Speaker 1: border guard lying in wait just inside our skin's castle wall.
Speaker 1: Our immune system is really complicated, and I am not
Speaker 1: a medical professional, y'all, I was an English major. But
Speaker 1: very basically, your epidermis and dermis each contain some specialized
Speaker 1: immune cells that can contain and neutralize any invaders. They
Speaker 1: can also call in backup from other immune cells that
Speaker 1: exist throughout the body via chemical signaling that creates inflammation.
Speaker 1: If you think about the last time you got a
Speaker 1: scrape or a cut, you may have noticed that it
Speaker 1: got reddish or purplish and puffed up a bit. That
Speaker 1: inflammation may be uncomfortable, but it's our body's way of
Speaker 1: getting extra supplies to the site of an injury to
Speaker 1: prevent infection and heal everything up. Once that backup arrives
Speaker 1: to the site, all of the immune cells work together
Speaker 1: inside the skin to clear out invaders and cellular debris.
Speaker 1: When they're done, other cells call off the inflammation and
Speaker 1: everything goes back to normal. The physical barrier is restored,
Speaker 1: and the immune barrier steps down from red alert to
Speaker 1: a state of watchful preparedness. Of course, this is assuming
Speaker 1: that everything is operating normally. The creation of the physical
Speaker 1: barrier and the responses of the immune barrier are both
Speaker 1: extremely complex processes, and unfortunately, any number of things can
Speaker 1: upset them, either from the outside in or the inside out,
Speaker 1: or both. Just for example, that lipid mortar around corneocytes
Speaker 1: gets produced by the corneocytes themselves as they develop into
Speaker 1: their final form. So if anything changes in the cells
Speaker 1: developmental process, say if it moves too fast, that doesn't
Speaker 1: just disrupt how those corneocyte bricks stack up. It can
Speaker 1: also disrupt the formation of the mortar around them, and
Speaker 1: having too much or too little of any component in
Speaker 1: the bricks or the mortar changes the way that the
Speaker 1: wall holds together. From the outside, our skin can become
Speaker 1: brittle if our environment is too dry, but it can
Speaker 1: also get flaky if it's too humid. Exposure to irritating
Speaker 1: or allergenic substances can cause an overactive immune response. Getting
Speaker 1: too much sun does cellular damage that your skin has
Speaker 1: to repair, which when repeated, will reduce cellular function over time.
Speaker 1: Even our mental health and stress levels are tied into
Speaker 1: how our organs function, and our skin certainly is an exempt,
Speaker 1: as anyone who's ever gotten a ZiT before a big
Speaker 1: event can tell you. From the inside, there are a
Speaker 1: number of diseases and conditions that muck about with some
Speaker 1: part of the skin barrier's upkeep, resulting in itchiness, flakiness,
Speaker 1: or other discomfort at best. For example, we talked recently
Speaker 1: on the show about psoriasis, a condition in which a
Speaker 1: combination of skin cell overgrowth and immune system freak out
Speaker 1: creates uncomfortable, scaly, or discolored patches that come and go,
Speaker 1: triggered by those outside stressors that I mentioned. If you
Speaker 1: or someone in your care experiences chronic skin barrier disruptions
Speaker 1: that result in that kind of issue. Definitely talk to
Speaker 1: a medical professional about the best way or ways to proceed.
Speaker 1: There are lots of topical and systemic treatments that can
Speaker 1: help control activity in the immune system or the skin,
Speaker 1: and a healthcare provider will be able to help you
Speaker 1: with the diagnosis and a plan. That being said, even
Speaker 1: finding a regimen that keeps quote unquote normal skin happy
Speaker 1: can be a challenge because the skin barrier is so
Speaker 1: complex that its exact functions are really pretty unique to
Speaker 1: all of us, and it changes over time. Simply getting
Speaker 1: older means that our skin structure thins and becomes less
Speaker 1: elastic and develops a different balance of immune cells. These
Speaker 1: changes in our skin barrier make us more susceptible to infections.
Speaker 1: A specialist like a dermatologist or esthetician may be able
Speaker 1: to help find exactly the right kind of moisturizer and
Speaker 1: other products for you, but the top level advice is
Speaker 1: to prevent skin barrier damage in the first place by
Speaker 1: treating your skin gently, protect it if you're going to
Speaker 1: be handling harsh chemicals or going out in the sun,
Speaker 1: and don't over cleanse after all, if your skin is
Speaker 1: your castle, your first duty is to respect such a
Speaker 1: grand structure. Today's episode is an original written by me.
Speaker 1: Brain Stuff is production of iHeartRadio, produced by Tyler Klang.
Speaker 1: Four more podcasts my heart Radio, visit the iHeartRadio app,
Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.