Did you know that your skin (called derma in Greek) is your largest and most diverse organ? It is a so-called surface organ and covers - depending on the anatomy of a person - with an area of about two square meters and a thickness of usually less than 0.1 mm the entire organism. Its most important task is to protect the organs from the damaging influences of the outside world and from dehydration. In order for it to be able to do this, however, it must be treated gently and cared for well. If your skin is not well, then usually your body and/or your soul is not well either. It reflects your inner life and shows you clearly when something is missing. Conversely, a damaged skin can also burden your soul. Therefore, we would like to explain to you in this article the basics of the skin structure and its many tasks. 

• Skin layers: Structure of the skin
• The epidermis as an outer protective barrier
• The dermis - elasticity, pressure and perception
• Functions of the dermis
• The subcutis - protection and power
• In a nutshell: The tasks of your skin
• Structure of the skin on hands and feet
• FAQ
• Sources

Skin layers: The structure of the skin

If you were to look at your skin under a microscope, you would see a complex structure. It is essentially made up of three major layers, which from the outside in are called the epidermis, dermis and subcutis. Each layer has a different composition and its own unique functions.

The epidermis as an outer protective barrier

Your outermost skin, called the epidermis, is made up of several layers of skin that are sealed off from the outside by dead, so-called stratum corneum cells (the stratum corneum). The surface of the stratum corneum is covered by a greasy film, the acid mantle.

Because the stratum corneum wears out quickly, it must be renewed regularly. Therefore, underneath it lies the germ layer, which forms new cells and slowly but steadily pushes them outward. About every four weeks, the stratum corneum is replaced by new cells.

During their migration outward, your stem cells from the lowest layer change into keratinocytes, which increasingly keratinize, flatten and become the aforementioned stratum corneum cells. Together with the pigment-forming melanocytes and the Langerhans cells of the immune system, they form the prickle cell layer.

Composition of the epidermis

Your epidermis consists of a total of five layers. If you look from the outside to the inside, then these are: 

• The corneal layer or stratum corneum as a separating layer to the outside.
• The shiny layer or stratum lucidum with transparent cells to protect against mechanical stress.
• The granular layer or stratum granulosum, which keeps the epidermis supple by producing fat (sebum).
• The prickle cell layer or stratum spinosum containing Langerhans cells as part of the skin's immune system.
• The basal layer or stratum basale with melanocytes as pigment images and as production site of new skin cells and the Merkel cells as nerve cells [4; 7].

 

The last two are also collectively called the germinal layer (stratum germinativum). The basal layer ensures the regeneration of the skin. With age, however, cell renewal increasingly decreases, and the skin becomes drier and more wrinkled. 

Function of the epidermis

The epidermis is the outer barrier layer of your body and protects it from harmful substances, injuries and germs from the environment. The melanin of the melanocytes converts UV radiation into heat and thus protects your skin from damage and burns, the Langerhans cells present harmful substances to the immune system. In addition, the horny layer thickens during strong sunlight, which can filter the rays better. You can influence the texture of the epidermis, its moisture and fat content through skin care products.  

The dermis - elasticity, pressure and perception

Your epidermis is joined inwardly by an elastic layer rich in collagen and connective tissue fibers: the dermis. This layer also contains blood and lymph vessels and various forms of skin appendages, such as hair roots, sweat and sebaceous glands, which penetrate through to your epidermis [2]. The sebaceous glands are always located near the hair roots.

This skin layer is also further subdivided. From the outside to the inside it consists of:

• The papillary layer or stratum papillare with papillae-like cones extending into the epidermis, immune cells and nerve fibers, and
• the reticular layer or stratum reticulare with sweat glands and hair roots.

 

Functions of the dermis

The collagen and connective tissue fibers in the dermis provide your skin strength, stability and elasticity, cushion pressure and shear forces. In addition, the dermis supplies your epidermis with oxygen and nutrients via the blood vessels and regulates the body temperature via them and the sweat glands.

The dermis also contains nerve fibers and sensory cells. They ensure that your brain can perceive information about the environment, touch, movement, vibration, pain, cold and heat [2; 4].

Important during care: The protective acid mantle

Sweat and sebum from the glands of the epidermis and dermis, together with dead skin cells, moisturizing factors, amino and lactic acids, form the protective acid mantle on the epidermis. With its slightly acidic pH value, it kills bacteria and fungi so that they cannot penetrate the skin.

In addition, an intact acid mantle protects your skin and your organism as a whole from drying out [5; 6]. If the pH value is too acidic, your skin will feel tight and dry and will have difficulty absorbing skin care products. If, on the other hand, it is too alkaline, the skin becomes oily and susceptible to germs. To keep this important barrier in balance, you should not take too many hot showers or baths and use pH-neutral cleansing and care products.. 

The subcutis - protection and energy

The epidermis and dermis form the so-called cutis, which is adjoined by the subcutis of connective and fatty tissue (stratum reticulare) [1]. It is connected with tendons, bones and fasciae and enables the displacement of the entire skin. The so-called Ruffini corpuscles, connective tissue capsules with receptors, report the stretching of your skin to the brain.

In addition, your subcutis contains sweat glands, blood vessels, hair roots, nerve fibers and receptors that signal your brain about the position of your body parts, pressure and vibrations, among other things - so-called Vater-Pacini lamellar corpuscles. Hair roots and hairs are involved in the thermal regulation of the skin. The roots are connected to muscles so that they can raise the hair when it is cold (goose bumps). In addition, sensory cells at the roots report to the brain any movement of your hair, such as by wind or touch [3; 6].

Function of the subcutis

The subcutis protects your underlying bones, muscles, joints and organs from pressure and shocks and acts as a reliable insulating layer to ensure that heat remains in your body. It also reports severe pain to your brain via special receptors [2; 4; 6]. Your fat-rich tissue is also a kind of energy store. Via the blood vessels, fats can be released from the blood into the tissue and - vice versa - fat from the subcutis into the blood, for example when you are on a diet and need extra energy. The thickness of this tissue depends on the amount of a person's body weight. In people with higher weight it is thicker, in underweight people it can sometimes disappear completely.  

In a nutshell: The functions of your skin

All in all, your skin not only gives your body shape and support, but also has some additional properties and functions. Fortunately, it is stretchy and elastic, otherwise you would move like a robot. It is permeable, for example to moisture, but it can also store moisture and fat. In addition to the above-mentioned functions, your skin can, in a healthy state:   

• Protect your organs from injuries, pathogens (such as fungi, viruses, bacteria), harmful substances, heat, cold and sunlight,
• prevent major water loss and heat accumulation in the body, or regulate body temperature through sweating,
• form vitamin D,
• detoxify to a small extent through the sweat glands,
• inform your brain through special tactile, heat and cold receptors, lamellar corpuscles and nerve endings about the position of the body and sensory stimuli such as pressure, pain and temperature, and
• indicate your mood, for example, by blushing, paling, or forming fear sweat [2; 5].

 

Your skin is a protective organ, a sensory organ and a detoxification organ, but also a means of expression for your health and emotions. All these functions show that your skin wants to be well cared for so that it can reliably fulfill its tasks.

Structure of the skin of the hands and feet

The skin is not the same all over your body. At the body openings, for example nose and mouth, the skin merges into the mucous membranes. While it is divided into fields on the rest of the body, your skin on the palms of your hands and feet provides more grip by forming parallel furrows (groin skin) and is more keratinized. These areas have no hair or sebaceous glands [6]. 

FAQ

What are the layers of the skin called?

Your skin consists of three layers - the epidermis, the dermis and the hypodermis. These three in turn are different in structure and function. Each skin layer is interlocked with the neighboring one by a special connection. The surface of your skin consists mainly of the corneal layer, which shields the organism from harmful external influences and ensures that water remains in the cells. The skin surface is covered by a transparent hydro-lipid film, the so-called acid mantle, which keeps your skin supple and reliably fights pathogens. It is formed, among other things, by a secretion from the sebaceous glands and salty water from the sweat glands. Your epidermis is followed by the dermis, which nourishes the skin cells via the blood vessels and transmits sensory stimuli to the brain. The lowest skin layer is particularly rich in fat and buffers the internal organs against shocks. It is both an insulating layer to protect against heat loss and an energy store from which the body obtains fats in times of need. It is also the only place where special receptors are located that signal severe pain to the brain.

What are the 5 layers of the epidermis called?

The epidermis, as the outermost layer of the skin, is divided into five further layers. Based on their appearance and function, they are called stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum and stratum basale. This fine subdivision goes hand in hand with the specific tasks of each cell layer. For example, the stratum corneum shields the skin from the outside, the stratum lucidum protects the cells from mechanical stress, the stratum granulosum keeps the skin supple with the skin's own oil production, the stratum spinosum performs an immune function, and the stratum basale supplies new cells and the skin pigment as protection against UV radiation..

Do humans have 7 layers of skin?

What is not visible from the outside is that the structure of the skin is much more difficult than it appears. The skin, or rather the cutis made up of the epidermis and dermis, is divided into seven closely interconnected cell layers in all parts of the body. Each layer contributes in a different way to the maintenance and tasks of the skin. Diseases of the skin can only be prevented if all of them interact in a healthy way. They ensure that your organism can maintain a constant temperature, fight germs and harmful substances from the outside world, protect the organs, produce vitamin D and report stimuli to the brain. These multiple functions of the skin make it particularly worthy of protection and require that it is well supplied with moisture, lipids and nourishing substances from the inside and outside.

What are the tasks of the 3 skin layers?

Your skin is a complex organ. The function and structure of the skin and its appendages are correspondingly diverse. A healthy skin must be able to resist damaging external influences, protect the organs and keep the organism in balance. For this purpose, the uppermost epidermis consists of a layer of cells that shields the organism and ensures that pathogens are killed, the skin remains supple and water is kept in the cells. Adjacent to your epidermis is a layer of cells that nourishes the skin cells through the blood vessels and transmits sensory stimuli to the brain. The lowest subcutis is particularly rich in fat and protects the internal organs from damage caused by impacts. As an insulating layer, it protects your organism from heat loss and provides energy reserves in the form of fats. Here are also special receptors that report severe pain to the brain.