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The skin
largest organ
2 m  surface area
more or less 5 kg / weight


The skin one

complex organ

by Alessia Capra



A. The Skin :
A vital organ with multiple functions



The skin, the largest external organ of the human body, covers almost 2 square metres to protect the delicate structures it envelops. But the skin is not just a simple covering; it is a complex entity with varied functions that go far beyond protection. In this article, we explore its sophisticated structure, its remarkable flexibility, its impressive protective capacities, and its astonishing ability to regenerate itself.

I. The Structure of the Skin

The different layers of the skin

The skin is made up of three main layers:

  • The epidermis: the outer layer, which acts as a barrier against external elements.

  • The dermis: located beneath the epidermis, it contains nerves, hair follicles and glands.

  • The hypodermis: the deepest layer, mainly composed of adipose tissue that insulates and protects the body.

Cells and functions

Each layer is populated by different types of cells, such as keratinocytes, which form the protective barrier, melanocytes, which produce skin pigment, and Langerhans cells, which play a crucial role in the skin's immune system.

II. Supple Skin

Skin is surprisingly elastic. This suppleness is mainly due to two proteins: collagen and elastin. Collagen gives the skin its robustness, while elastin allows the skin to regain its shape after being stretched. This ability is crucial for body movement and also contributes to the skin's resilience to injury.

III. The Skin's Protective Role

Physical barrier

The skin protects us from micro-organisms, harmful chemicals and ultraviolet radiation from the sun. It also acts as a mechanical shield against physical trauma.

Immunological barrier

The skin's immune system is always on the alert to detect and combat pathogenic invaders. When attacked, the skin's immune cells react quickly to neutralise the threat.

Thermal control

The skin also regulates body temperature through perspiration and the dilation of blood vessels, helping to maintain a stable body temperature.

IV. Skin Regeneration

The skin has the remarkable ability to repair itself when damaged. The healing process takes place in several phases: inflammation, formation of new tissue, and remodelling of the tissue. This cycle of cell renewal is essential for maintaining healthy, youthful skin.

V. Conclusion

The skin is much more than just a surface. It is a complex, dynamic organ that plays a crucial role in protecting, regulating and maintaining our general well-being. Taking care of your skin means taking care of your overall health.

B. Skin diseases

Skin diseases can vary considerably in terms of frequency, severity and symptoms. Here is an overview of the most common to the rarest dermatological conditions:

Common skin diseases

  • Acne: This is the most common skin disease, mainly affecting teenagers and young adults. It is caused by obstruction and inflammation of the hair follicles and sebaceous glands.

  • Eczema (atopic dermatitis): A chronic condition characterised by itchy, red skin rashes. It is often linked to allergies and asthma.

  • Psoriasis: A chronic inflammatory disease which causes an overproduction of skin cells, forming thick, scaly and often silvery patches on the skin.

  • Contact dermatitis: Skin reaction caused by contact with certain irritant or allergenic substances, often manifested by redness, itching or blistering.

  • Urticaria: Sudden skin eruptions manifested by severe itching and raised red patches, often due to an allergic reaction.

  • Fungal infections: For example, athlete's foot or ringworm, which are caused by fungi that thrive in warm, damp environments.

Less common skin diseases

  • Rosacea: Characterised by facial redness, small visible blood vessels, papules and pustules. It mainly affects fair-skinned adults.

  • Vitiligo: Loss of skin pigmentation, manifested by the appearance of white patches on the skin, resulting from the destruction of melanocytes.

  • Impetigo: A highly contagious bacterial skin infection, often found in children, characterised by red lesions which develop into vesicles and then yellowish crusts.

Rare skin diseases

  • Cutaneous lupus: A form of lupus that affects only the skin, causing rashes, often in response to sun exposure.

  • Scleroderma: An autoimmune disease characterised by hardening and tightening of the skin and connective tissue.

  • Pemphigus: A rare autoimmune disease characterised by blistering of the skin and mucous membranes.

  • Xeroderma pigmentosum: Rare genetic disorder in which the skin is extremely sensitive to ultraviolet rays, leading to a high risk of skin cancer.

  • Epidermolysis bullosa: A group of rare genetic disorders causing extreme fragility of the skin, where blisters can form in response to minor trauma.


These conditions can vary in terms of treatment, ranging from topical application of creams or ointments to more complex therapies such as immunosuppressants or phototherapy. Each condition requires a specific approach, often managed by a dermatologist.

Lagap SA offers a number of interesting and even original treatments in various galenic forms.

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