The skin is the human body’s largest organ, and taking care of it is very important to your health.

It is our external barrier, and its essential function is to protect the body from the environment. It is considered a single organ, because it functions systematically. It is very large, with a surface area of approximately 2 m2 and it weighs 4 kg, accounting for about 16 % of your total body weight. The skin is constantly replenishing itself and changing.


What is the function of skin?


The skin acts like a protective shell against mechanical, chemical, toxic damage and pathogenic micro-organisms. It also contains melanocytes and other structures, which protect the skin from ultraviolet rays.

Hydroelectrolytic balance

It keeps body fluids in balance, acting as a barrier against possible water loss.


We reveal your mood through our skin, by blushing, going pale, our hair stands on end and we give out a smell (pheromones).

Temperature regulation

The skin acts like a thermostat, adjusting to hot and cold temperatures to regulate body temperature.


It transmits sensations of touch, pressure, temperature and pain through nerve receptors and nerve endings.


From the outermost to the innermost level, there are three layers of tissue, of different embryological origins:

The epidermis

The epidermis consists of flat polystratified keratinised epithelial tissue that covers the entire body surface. This layer of skin has the largest number of cells and an extraordinarily large rate of renewal. Cells grow from the inside (basal layer) to the outside (horney layers). It varies in thickness (from 0.1 mm to 1 or 2 mm on the palms of the hands and the soles of the feet).

Cell types

Keratinocytes (90%)

Produce keratin, which gives cohesion to the tissue and waterproof the dermis.
Melanocytes (5-10%)

Synthesise melanin, which is our natural pigment and protects us from ultraviolet radiation. Skin does not depend on their number, but rather on their size.
Langerhans cells (2-5%)

Are immune cells.
Merkel cells

Are the sensory cells.

The epidermis is divided into layers or strata

Basal layer
Where the keratinocytes are produced.

Spinous layer
The keratinocytes are spindle shaped, and start producing keratin fibres.

Granular layer
The cells produce keratohyalin granules (the precursor of keratin) and these go into the extracellular matrix.

Clear layer or stratum lucidum
Cells have been flattened to confer a greater degree of structure.

Horney layer
This is the outermost layer, which contains many layers of dead cells that offer protection. These cells come loose, through a process called scaling. The sebaceous and sweat glands empty into this layer.

Subcutaneous tissue (hypodermis or subcutis)

This consists of loose connective tissue which serves as an anchor. When these bridges are lost, the typical wrinkles appear. It is made up of adipose tissue, through which blood vessels and nerves run. The subcutaneous tissue serves as an energy store, as well as providing thermal insulation and mechanical protection.

The dermis or chorion

This structure supports the skin and gives strength and elasticity. It is mainly made up of fibroelastic connective tissue. It is much thicker than the epidermis.

The extracellular matrix contains a high proportion of fibres, loosely compacted, collagen (> 75%), reticulin and elastin. It is vascularised tissue that supports and nourishes the epidermis. It accounts for the largest mass of skin and has a maximum thickness of about 5 mm.

This is where the nerve endings responsible for touch and pressure are found, as well as skin appendages:

Piloerector muscle, hair follicle, sebaceous glands, and sweat glands, and blood and lymphatic vessels.


Understanding your skin is the first step to knowing what it needs and how to take care of it.


Dry skin tends to flake and crack. This happens when it produces a lower concentration of lipids to retain water molecules in physiological form, absorbs less moisture or is subjected to more aggression.

Treatment for dry skin should focus on regeneration and moisturising.


Mixed or combination skin consists of several skin types.
Parts of the skin on the face and body behave differently.
This is usually very noticeable on the face, where there is variability in the so-called T-zone (forehead, nose and chin), which look oilier.
Pores are open, skin is shiny, secretes more oil and feels greasier to touch, while the cheek area tends to have normal or dry skin.


Oily skin tends to have excess sebum, which has numerous effects: shine, open pores, build up of dirt in the stratum corneum (blackheads, pimples) and acne caused by blocked pores.

This type of skin must be controlled with astringents and proper care.


Sensitive skin reacts and is affected by any change. It tends to be caused by allergies or external agents.

Preventive care is required.


Normal skin is balanced skin. It is neither shiny nor dull, and there are usually no circulatory problems. It is smooth and soft, firm and looks moisturised, without flaking.


Aging (types of aging)

The tissue regeneration that enables physiological oxidation of the tissue slows over the years.

The epidermis becomes thinner and less efficient at regeneration. The dermis produces less collagen, which causes greater flaccidity. Fat cells are lost from the subcutaneous tissue, decreasing its volume and elasticity.

This happens naturally and the visible effects are the wrinkles and expression lines that gradually appear. The skin loses volume and firmness (lower tissue density).

Genetic or chronological aging

This is the most common and physiological type. It depends on genetics, race and predominant skin type.

Prevention is essential to its adaptation.

Induced aging or photoaging

Exposure to the sun is the main external factor responsible for skin aging. Solar radiation causes tissue oxidation, which damages the skin, decreasing its ability for regeneration and protection. This continuous damage wrinkles the skin’s surface and changes its pigmentation.

Pollution, smoking and malnutrition are significant factors that accelerate the natural aging process.

Hormonal aging

This type of aging affects women and is mainly due to falling levels of oestrogen at menopause.

Lower hormonal levels speed up collagen loss in the dermis, decrease elasticity, skin thickness, and intercellular cohesion. In addition, there is a reduction in hydration, with changes in the pigmentation and the dreaded drop in the cell renewal.


Blotches and skin marks, or melanoderma are produced by a change in the process of natural pigmentation of the skin.

Melanin is the substance that gives skin its colour. Melanin build-up (hyperpigmentation) or lack of melanin (hypopigmentation) causes different types of marks:

Hyperpigmented spots (hyperchromia)


Malignant neoplasm of the melanocytes, with irregular edges and with abnormal pigmentation that grows steadily and can cause distant metastases. We recommend that if you have any questions about any marks or spots on your skin, you see your dermatologist (Asymmetric, Edge, Colour, Diameter, Evolution, Rule).
Liver spots

These are the most common and are linked to sun exposure.
Melasma or chloasma

This is a brownish area that can be aggravated by the oestrogen peak during pregnancy.

After a tissue inflammation, like a wound, more deeply pigmented areas can develop.
Melanocytic Nevus

These are circular melanocytes (moles) that may be raised.

Hypopigmented spots (Hypochromia)


Vitiligo is an autoimmune disease that causes pigmentation to disappear.


Acne vulgaris is a skin condition characterised by an excess production of sebum, which tends to appear in adolescence. This is when the body reaches the androgenic peak necessary for the development of the sebaceous glands.

There are different types of skin lesions (comedones, papules, pustules and nodules).

It is characterised by follicular epidermal hyperproliferation (the cells do not flake off), excess sebum production that blocks the pores, and lesions that cause inflammation and increase in the activity of Propionibacterium acnes.

There are several clinical forms, such as excoriated acne, acne caused by cortisone and acne conblobata.

Excessive Sweating

Excessive sweating or hyperhydrosis happens when more sweat than is physiologically normal is produced.

It affects 2 % of the general population, and there are different therapeutic alternatives, such as topical antiperspirants, botulinum toxin infiltration, iontophoresis, anticholinergics, beta-blockers, antidepressants and even endoscopic sympathectomy.

Rosacea or couperosis

Rosacea is a chronic skin disorder that affects the face and produces attacks of redness (flushing) and permanent injuries in the central area of the face (cheeks, forehead, nose, mouth and chin).

It can cause vascular dilatations (telangiectasisas), papules-pustules (lesions containing pus), flushing, ocular symptoms (itching or blepharitis) or thickening of the surface of the skin that affects the nose (rhinophyma), forehead, cheeks, chin, ears or eyelids.

This treatment is based on skin protection (before exposure to ultraviolet radiation, the cold, etc.), skincare (hypo-allergenic soap) and oral treatments (tetracycline, isotretinoin, sulfones) and topical products (metronidazole, ivermectin, azelaic acid).

In many cases, rosacea can be mistaken for other skin conditions, such as atopic dermatitis or acne, because the symptoms can appear similar to the naked eye.


Bruises or haematomas are caused by bleeding within the skin when blood vessels are damaged by an injury.

Their frequency depends on capillary fragility.

Their clinical evolution starts with a bright red appearance with inflammation, which turns purple. This happens because the blood starts to coagulate and is then absorbed.

The blood may accumulate within the skin tissue as petechiae (red dots), purple bruises (larger flat areas) or ecchymosis (areas of large haematomas).

This is not to be confused with an erythema, which is a reddening of the skin that becomes paler when pressed.

In many cases, rosacea can be mistaken for other skin conditions, such as atopic dermatitis or acne, because the symptoms can appear similar to the naked eye.


The skin becomes dehydrated when it loses water. This accentuates expression lines and causes increased flaking. It can also be associated with dryness, rash and inflammation.

This happens when the layers of skin are unable to hold the necessary ambient moisture or water molecules. Starved of water, the cells die more quickly and the skin flakes because we lose cells that through a hydration structure in deep and surface layers could be maintained.

By adding emollients, this structure is preserved, because water molecules remain in the skin, which can continue to perform its barrier functions. In addition, if we reduce the adverse conditions (ultraviolet radiation, cold, heat, humidity, etc.), we can make skin firm and bright again.

Sensitive Skin

Sensitive or intolerant skin is unable to withstand the use of topical substances and it reacts to contact with these, causing itching, swelling, irritation and erythema.

This is usually due to an underlying skin disease such as rosacea, dermatitis (atopic dermatitis or seborrheic dermatitis) or contact eczema.

The strategy for treating sensitive skin is to prevent contact with these irritants, and daily care with hypo-allergenic and non-irritant substances.



Human hair is a keratinised structure that goes through three stages of normal development (hair cycle):

Anagen phase (or growth phase)

Which lasts between two and six years. The hair emerges and grows one centimetre per month on average. The follicle is always active. A total of 90% of the hair on your head is in this phase.

Catagen phase (or resting)

Is a stable phase that usually lasts about three weeks. Hair stops growing and falls out of the papilla.

Telogen phase (or fall)

In this phase, the follicle rests and hair starts to fall out. This takes around 2-5 months.

Hair follicle

Basically, hair follicles contain the hair, which is a keratinised structure emerging from an epidermal invagination. It is deep inside (dermal papilla), where it receives the cellular nutrition. The content excreted by the glands empties into the follicular infundibulum:
Sweat glands

Control temperature, excrete water and other substances (salt, ammonia, uric acid, urea, lactic acid). These glands also produce odours, secreting a substance that quickly becomes contaminated and generates the familiar body odour.
Sebaceous glands

Produce lipids that help to maintain the protective layer.

Each hair grows from a follicle and each follicle has its own cycle, which is independent from those surrounding it. That is why each hair on your head is in a different phase of its life cycle, at any given time. There are between 100,000 and 150,000 hairs on the head of a person without alopecia, of which 85%-90% are in the anagen phase or growth period, 1-2 % in the catagen or resting phase, while 13-14 % are in the telogen or fall phase.







Hair loss

We know that for every 100 hairs that we have, there is always one in the 12-15 % replacement phase and it can take around four years to completely renew all our hair.

On average, in one day around 70-100 hairs are lost. In normal conditions, these are replaced by new ones generated by the hair follicle.

Eight in ten people who believe that they have alopecia,do notpathological substrate. All that is happening is that we are losing hair randomly and this is not replaced immediately. Therefore, the concept is based on renewal of the hair follicles rather than hair loss. This process, called telogen effluvium, is often seasonal and depends on various factors (the environment or food).

However, there are also genetic factors that affect the speed at which the renewal process occurs, which means that hair falls out at a different speed to the natural renewal process.

Types of hair loss

Diffuse alopecia | Non-scarring alopecia

Reversible and not localised in a certain portion of the scalp.

Alopecia areata | Non-scarring alopecia

Causes circular bald patches and is usually reversible.

Traumatic or drug-induced alopecia | Non-scarring alopecia

Caused by trauma or pressure. It is also caused by trichotillomania which is the nervous habit of hair pulling.

Androgenetic alopecia | Scarring alopecia

This type of alopecia destroys the hair follicle. Hair loss is irreversible:

Hereditary diseases: Ichthyosis, Darier disease, etc.
Infectious diseases: Fungal, bacterial.
Neoplastic diseases: Lymphomas, metastases, etc.
Dermatosis: Lichen planus, systemic lupus erythematosus, sarcoidosis, etc.