Tasks of the skin: what an organ

Shoulder of a woman with a heart of cream

Our skin is not only the largest organ, but one that performs many more tasks than we often realize. The functions of the skin are decisive for our state of health. It is not only about skin problems, but also about the right body temperature, sun protection, dehydration and much more.

But, let's face it: when it comes to our outer shell, we quickly tend to be strict and are rarely really happy: we meticulously examine pores, spots and wrinkles. Above all, however, we reduce the condition and significance of our skin to the area we first see in the mirror every day - our face. In doing so, we fail to do justice to the magnificence of this organ. In this article, we will therefore focus on the entire two square meters of skin that perform peak performance for us and our body around the clock.

The skin (Greek: derma) of our body fulfills the following tasks - and many more - in an exemplary manner:

Corset & shaper of the body

The most obvious function of the skin: it holds our internal organs and blood vessels together and, together with the skeleton and muscles, ensures that our body stays in shape and everything stays in place. After all, you only want your heart (if at all) to literally slip down your pants! The tensile strength of the skin required for this is enormous, just think of leather. But it also has its limits: stretch marks, for example, are the visible result of overstretching the skin.

The skin as a protective shield & watchdog

Healthy skin follows a strict door policy: With its upper layer, it prevents water, germs and environmental toxins from entering our body. It succeeds in this because the optimal pH value of our skin is between 4.5 and 5.5. This slightly acidic environment ensures that the skin neutralizes alkaline substances (e.g. urine, stool, alkaline soaps) and prevents the growth of bacteria and fungi.

To a certain extent, the skin (with the help of its pigments and outer horn cells) can even neutralize harmful UV radiation. In the event of an incident, it warns us like a barking watchdog via pain receptors of fire or (imminent) injury and informs our immune system of intruders that have nevertheless managed to penetrate the barrier. For all its rigor, the skin is choosy: moisture, lipids or cosmetic active ingredients enjoy "VIP access".

The largest organ is water storage & air conditioning

The skin consists of about 70 percent water and thus stores about a quarter of the fluid in our body. The skin acts as an air conditioning system through the vital function of sweating: sweat evaporates through our pores as needed to cool down our organism. But it is not only sweating that helps to balance the temperature - the body precisely controls our body temperature by selectively dilating or constricting the blood vessels in the skin. Without this clever tactic, the temperature would rise to a life-threatening level after just 15 minutes of moderate exertion! But the skin can also warm the body: When it's cold, the veins constrict and sweat dries up. In addition, the fatty tissue of the subcutis insulates our body - an enormously important function of the skin.

The body own chemical factory & pharmacy

The glands in our skin produce sweat, fragrances and sebum. But it can produce much more: Around 30 different hormones are produced here, including those that relieve pain, promote skin pigmentation or control the formation of cortisone. Dermatologists therefore refer to the skin as the human body's largest source of hormones. One of the best-known hormones produced here is vitamin D, the "bone hormone. There are good reasons why it is produced in the skin: For one thing, sunlight is needed for vitamin D synthesis. On the other hand, it is used in part directly in the skin, because here it is largely responsible for a balanced moisture content.

Diplomat & Manager

Our skin is in constant dialog with our environment: it makes us sweat, makes us blush, gives us a glow or signals to our surroundings that we are unwell. It also provides the sense of touch, which is impressive in several respects: it is the first sense that a human being develops, namely as early as the eighth week of pregnancy. Incidentally, it is far superior to our eyes in terms of accuracy: Thanks to it, we can sense irregularities that are only 0.001 millimeters high. To see them, they would have to be 80 to 100 times that size!

Did you know? The weight of the skin is 3.5 to 10 kg, depending on the height and weight of the person. If the fatty tissue is included, it can even reach a weight of 20 kg.

Multi-shift operation: The structure of the skin

In order to fulfill these many tasks in the body, a complex structure of the skin is necessary. Don't worry, I'm not going to present you with a detailed medical treatise in the following. Nevertheless, it is worth taking a closer look at the different layers of the skin - these are essentially the epidermis, the dermis and the subcutis. All three skin layers are closely interconnected, but each has its own tasks.

The subcutis - our upholstered furniture

Let's start at the bottom: This is where the subcutis lies. Nerve endings, blood vessels, hair roots and glands from the upper layers still partially protrude here. However, the subcutis mainly serves as a cushion and therefore consists of loose and very stretchable connective tissue. The majority of the subcutis is made of fat cells, which are divided into different large groups by septa. These "fat lumps" can sometimes be seen from the outside - as cellulite. Although we often look at them with an ungracious eye, these fat cells have important functions: They dampen heat and cold, but also shocks. At the same time, they are an energy reservoir. In underweight people, the hypodermis can disappear completely, while it is particularly pronounced in overweight people.

Cross-section of the skin with all components such as nerves, blood vessels, various cells, etc.
The main components of the skin: (1) nerves, (2) blood vessels, (3) hair root, (4) fat cells, (5) connective tissue, (6) hair follicle muscle, (7) sweat glands, (8) lymphatic vessels, (9) germ cell, (10) pigment cell, (11) Langerhans cell, (12) sting cell, (13) granule cell, (14) horn cell.

The dermis - robust control center

Directly above this is the dermis, or leather skin. There is a lot going on here: it is densely interwoven with blood vessels and connective tissue fibers. It receives signals when our skin is irritated or even endangered from the outside. Then the dermis pumps blood vigorously upwards. This results, for example, in wheals or pustules in the case of an allergic reaction. In the event of an injury, for example an unfortunate cut with a kitchen knife or an insect bite, the skin immediately sounds the alarm and sends pain signals to the brain. The hair roots are also located in this skin layer, as are the sweat and sebaceous glands.

Together with the blood vessels, they turn the dermis into a "regulating machine": Via blood circulation, the skin is heated up when necessary, and cooled down by sweating. The elastic and tough connective tissue ensures that the skin returns to its original shape after being pulled, plucked or pressed. Responsible for this are connective tissue cells called fibroblasts, a special protein molecule called collagen and the highly elastic fiber elastin. Together, they form the reticular layer. With increasing age, these fibers wear out; then the skin loses its youthful elasticity. And the delicate body hairs also contribute to temperature regulation: Next to each hair follicle sits the small hair bellows muscle, which raises the hair when it gets cold, thus binding a protective layer of air above the skin's surface. Last but not least, the sebaceous glands ensure a constant supply of skin oil, which helps to form our protective acid mantle and thus keeps water loss in check. For people with oily skin, these glands mean particularly well. The dermis not only regulates, but also spies. A dense network of lymphatic vessels also runs here. The lymphatic system is more or less the outpost of our immune system: it spies out unwanted skin invaders such as germs and other pathogens and eliminates them with an army of killer cells. Quite a lot of action!

The epidermis - hard shell and yet quite delicate

Above the dermis is the epidermis. It forms our outer, visible shell - a kind of highly efficient defense wall. Much of the multitasking described above falls within its remit. Therefore, it has a number of specialized cell types - for example, horny cells, pigment cells and palpatory cells. Not to be forgotten: the Langerhans cells. These immune cells always keep a close eye on whether the skin is threatened by germs or other irritants and, if necessary, send cries for help down to the busy dermis. Both skin layers are connected by wave-shaped indentations so that the dermis can supply the adjacent skin layer with nutrients.

The structure of the epidermis is similarly complex as its tasks. It consists of four to five layers (depending on the region of the body): The epidermis can be further subdivided from the outside inward into the horny layer (stratum corneum), the shiny layer (stratum lucidum), the granule cell layer (stratum granulosum), the prickle cell layer (stratum spinosum) and the basal layer (stratum basale).

At the same time, it is responsible for our appearance, because up here what is not running optimally further down in our skin becomes visible: for example, on the face in the form of shimmering eye circles, impurities, redness or pigmentation spots. On the feet or palms of the hands, you see much less of what's going on under the skin. This is due to the fact that it is much more stressed here. That's why the upper layer of the epidermis, i.e. the horny layer, is much thicker here - that's why it's called callus.

The layers of the epidermis are never at rest. On the contrary: they are always in motion! In order to always be in top shape, the epidermis continuously renews itself. In fact, this is its main task: to constantly rebuild the upper skin barrier throughout life. Because only in this way can the skin maintain its central function as a protective shield against external influences.

Change of layers: your skin renews itself

Natural skin renewal, also called exfoliation, is a fascinating process and of utmost importance for our skin health. It takes place from the inside out, or more precisely from the bottom up: In the lowest layer of the epidermis, the basement membrane, fresh germ cells grow around the clock. On their way to the surface, they first become spiny cells and then granule cells. On this journey, which lasts about 4 weeks at a young age (twice as long at an advanced age), their composition and their field of activity thus change several times. They are always useful: in the course of their journey to the surface, they produce the protein keratin (also called horn), special fats (known as ceramides) and other types of protein. On their strenuous journey, the epidermal cells gradually run out of air - they become flatter and flatter. Almost at the top, they have turned into thin horny platelets. Last but not least, they lose their nucleus - it is (or was) the powerhouse of the cell. In other words: Now they are dead. On average, our skin sheds about 10 grams of lifeless skin cells every day in this way. Or to put it another way, we lose a staggering 50,000 horny cells every minute. 

As the cells of the epidermis grow, they migrate in four stages from the bottom
to the top. The times refer to young skin. With increasing age
the process of exfoliation slows down.

So it's good that new cells can flow in from below at any time. However, this happens more and more slowly with increasing age. The statement "Every 28 days our epidermis renews itself" is an average value. In people in their twenties, the skin is a few days faster, in the forties it already lags a few days behind. Beyond the age of 50, it can already happen that a skin renewal cycle takes twice or even three times as long!

With these products you can support your skin's own exfoliation

The skin needs help

With age, the vulnerability of the skin increases. The skin renews itself more slowly, many older people drink too little, mobility decreases. A major problem can arise when painful pressure ulcers (bedsores) develop due to bedriddenness and improper care. Once a pressure sore has developed, the healing process of this skin damage can take months and be very stressful. 

In order for our skin to perform its many important functions and remain healthy and resilient, we should treat it well throughout our lives. Fluid is extremely important for our skin health, but so is a balanced diet and exercise and the right care.

The most common skin diseases are presented in a separate article.