Functions and structure of the skin: the composition of the lipid barrier of the skin

The skin is the outer covering of the human body, which is responsible for its relationship with the environment. Leather – the largest organ of the human body, multifunctional and extremely complex in structure. It performs many functions, and the performance of these diverse functions takes place in constantly changing, often harsh and aggressive conditions under the influence of various environmental factors. What is the structure of human skin, and what is the role of the lipid layer? The main functions of the skin, read on estet-portal.com.

The structure of the skin: the life cycle of keratinocytes

The unique structure of the skin provides the above functions. The skin consists of three layers: epidermis, dermis and subcutaneous fat. Each of them has a special structure. Find out more about the composition of the lipid layer of the skin at estet-portal.com. Only the epidermis is available for direct exposure to cosmetic products, and mainly its stratum corneum.  

The main cell of the epidermis – keratinocyte

. The lowest layer of the epidermis is called the basal; keratinocytes of this layer are in a state of constant division. As they mature, keratinocytes move up to the surface of the skin, and the cells move in a single layer, which makes it possible to single out separate layers in the epidermis depending on the stage of development, or rather, on the stage of "dying"; keratinocytes. Main functions of the skin:

barrier;

• protective;
• thermoregulation;
• receptor;
• endocrine;
• excretory;
• respiratory;
• immune;
• vitamin-forming;
• social.

Things a beautician needs to remember about skin layers Structure of the lipid barrier of the skin

The upper layer of the epidermis is called the stratum corneum and is represented by corneocytes – cells that are filled with keratin protein and have lost the nucleus, as well as cell organelles. The sheath of corneocytes is called horny envelopes. They have the shape of a hexagon, fit tightly to each other, connecting with special protrusions – corneodesmosomes.

The space between the corneocytes is filled with a lipid-protein structure (the so-called lipid barrier of the skin), which “glues” corneocytes to each other. This structure of the skin ensures the integrity of the stratum corneum. The lipids of this barrier are composed of

ceramides,

cholesterol and its esters, and free fatty acids.

For healthy skin with good barrier properties, the proportion of ceramide/cholesterol/free fatty acids is 1:1:1. A change in this proportion leads to a violation of the entire structure of the lipid barrier and, as a result, to a weakening of the barrier function of the stratum corneum as a whole.

The lipid barrier is formed by alternating layers of lipids and water.

What are the functions of the layers of the skin

Despite the fact that the stratum corneum consists of dead cells, it is metabolically active due to the work of numerous enzymes. The stratum corneum is a reliable barrier to the path of various substances. The corneocytes themselves are practically impermeable, the passage of substances is possible only through the lipid layer.

Read on the topic: "

The ABC of the skin for a cosmetologist: the structure of the epidermis (part 1)

" This layer is impermeable to water-soluble compounds, and the passage of large molecules (eg proteins or polysaccharides) is also difficult.  The structure of the skin, in particular the stratum corneum, provides selective permeability of the skin for various substances.

The epidermis and dermis are permeated with free nerve endings that have special receptors for histamine and are highly sensitive to it.

Histamine is secreted by mast cells with very slight changes in the extracellular environment. The result is a sensation of

itching.

This skin structure provides an immediate reaction of the skin to the allergenic agent. Read on the topic: "

The ABC of the skin for a cosmetologist: the structure of the dermis (part 2)

" By blocking the penetration of water-soluble compounds, the stratum corneum also effectively protects the skin from excessive moisture loss, that is, from dehydration. Fat-soluble compounds not only pass through the epidermal barrier, but can also change its permeability to other substances. To increase the permeability of lipid layers, unsaturated fatty acids are added to the composition of external medicinal and cosmetic products, which are embedded in the lipid layer and reduce its viscosity.

Read on the topic: "

The ABC of the skin for a cosmetologist: The structure of the hypodermis (part 3)

The structure of the skin is important for cosmetologists and dermatologists to understand the ways and means of eliminating skin problems without harming its cells.