The SKIN – body’s first line of defense

skin structure Николай Лазаров Nikolay Lazarov


Where is the skin located?

The skin forms an effective barrier between the organism and the environment, protecting against the invasion of pathogens, chemical and physical attacks, as well as the uncontrolled loss of water and dissolved substances (salts, metabolites, etc.). It also helps with thermal insulation, temperature regulation, and as a receptor for some senses.


What is the skin?

Skin is the largest organ in the human body and forms the boundary between the body and the environment. It is a site of extensive interaction between the immune system and the microbial inhabitants. The latter include classic biofilm-forming pathogens and the skin microbiome. Imbalance (dysbiosis) in these societies leads to disruption of the homeostasis (balanced state; eg temperature regulation and acidity balance) and disease.
Human skin is made up of three main tissue layers: epidermis, dermis and hypodermis.
skin structure Николай Лазаров Nikolay Lazarov

The epidermis is the top layer of the skin and is made up of epithelial cells. It does not contain any blood vessels. Its main function is protection and participation in the maintenance of the homeostasis. It consists of four types of cells: keratinocytes, melanocytes, Merkel cells and Langerhans cells. The main type of cells that make up the epidermis are keratinocytes, which produce keratin. Keratin is a fibrillar (filamentous) protein that makes up the extracellular space of epidermal cells. Millions of keratinocytes are shed every day. A large part of the skin is keratinized and therefore waterproof, otherwise when bathing for example, some of water would enter freely through the layers and the human body would swell. All the microorganisms from our unique skin microbiome live on the surface of the epidermis. A healthy epidermis also ensures moisture retention inside the skin.

The dermis is the middle layer of the skin, made up of dense connective tissue in which collagen and elastin are interwoven, forming dense “tufts”. This layer gives elasticity to the skin by allowing it to stretch and contract, while at the same time protecting it from deformation, wrinkling and sagging. Blood vessels and nerves end in this layer. The dermis is where the chromatophores (cells that carry skin color) are located, as well as where the hairs grow and the glands (sebaceous and sweat) are located. The active cosmetic ingredients must reach this layer of the skin in order to affect the general condition of the skin, to strengthen or protect against wrinkles.
The hypodermis lies immediately below the dermis. It is made up mainly of connective adipose tissue. Its physiological functions are exhausted in insulation, energy reserve, as well as maintenance of the dermis.


What are the main functions of the skin?

Healthy skin is a dynamic system that flexibly adapts to changing environmental conditions, such as:

  • adapts heat loss to the outside temperature;
  • regulates water loss depending on temperature and humidity – “under normal conditions” between 0.5 and 1 liter per day;
  • eliminates salts (through the sweat glands) and lipid substances (sebum, “lipid mantle of the skin”);
  • serves as a barrier against foreign substances and microorganisms, including control of the pH level of the skin surface;
  • builds individual protection against stress caused by UV light;
  • protects against mechanical stress;
  • transmits pain, temperature and tactile stimuli (touch) through the nerves.


What skin types are there?

Each person is unique, and this does not only apply to character. There are many systems aimed at characterizing and classifying different skin types, but scientists have not reached a consensus. Broadly speaking, we can divide skin types into six types:

Normal skin has a smooth texture and a pink, flat surface with fine pores. There are no visible spots, oily or scaly areas. Sebum production, moisture content and exfoliation are well balanced.
Oily skin is characterized by an increased amount of sebum on the surface due to the overactivity of the sebaceous glands. The skin is shiny and dense, often with enlarged pores. It is prone to blackheads and other blemishes, occurs more often in men than women, and mostly affects adolescents and younger people.
Dry skin is characterized by a lack of moisture in its stratum corneum, which leads to tightness and even peeling. The skin looks lifeless, especially on the cheeks and around the eyes. It may lack elasticity, with accentuated fine lines and wrinkles. In more severe cases, itching and burning may occur. Extremely dry skin shows signs of cracking.
Dehydrated skin can be genetically determined or triggered by factors such as climate, cosmetics and medications. This can be a natural consequence of the aging process as sebum production decreases.
Combination skin is quite dry in some parts and oily in others. Combination facial skin tends to be dry on the cheeks and around the eyes, and oily in the T-zone (nose, forehead, chin). Dry and oily areas require different care. This skin type is very common.
Acne-prone / Reactive skin – With this skin type, sebum production is not well regulated, as a result of which the skin turns out to be a favorable environment for the development of bacterial species such as Propionibacterium acnes, Staphylococcus epidermidis and Malassezia furfur. Thus, the microbial balance shifts in favor of the harmful microflora and leads to the appearance of pimples, inflammation and subsequent hyperpigmentation of the affected areas.
Mature skin – As we age, the skin’s sebum production decreases, often leading to increased dryness, the appearance of fine lines and wrinkles, and flaking. The skin may look lifeless and itch. Another problem is hyperpigmentation, especially in individuals with a long history of sun exposure.

“Sensitive skin” is not exactly a skin type, but rather a symptom caused by various factors. People tend to describe their skin as “sensitive” if it often reacts with redness, itching, burning, or dryness to topical skin care products. The causes of this condition can be a hidden skin disease, allergies, contact with irritants in certain products or incorrect use of cosmetic products.


How to take care of your skin?

+ Apply sunscreen every day.

+ Monitor the type and size of your moles and freckles – if they grow fast, have an irregular shape or itch, it’s best to consult a dermatologist.

+ Use products that meet the needs of your skin. If you are not sure visit Personal Diagnostics by L‘ali.

+ Don’t use harsh exfoliating products more than once a week, and even then don’t use force.

+ Wash your face with appropriate products every morning, at night before going to bed and after sweating.

+ If you have sensitive skin, wash the cleansing products off your face with lukewarm water, even if you only use micellar water.

+ Drink enough water (according to weight, about 30 ml / 1 kg / day).

+ Diet and exercise may not seem directly related to healthy skin, but they are. Exercise as much as possible and eat a varied diet.

+ If you have any concerns about your skin or scalp, see a dermatologist.


This is an editorial prepared especially for you by Lali.
All rights reserved!

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