Skin physiology

Structure of the skin

The skin consists of three layers:

Epidermis – The thinnest of the layers of the skin. It consists of 5 layers of cells which continually divide and shed. Provides the outermost protective barrier to the skin. Dermis – The true skin. Provides the strength and resiliency of the skin, as well as many other functions. Contains many of the skin structures such as glands, nerve endings, blood supply, collagen and elastin. Hypodermis – The layer of fat below the dermis that stores energy, provides insulation and cushions against falls.

The dermis

Fibroblast cells in the dermis produce collagen and elastin and the gel matrix. These protein fibres and ground substance allow the skin to expand and to contract.

Amongst these substances are the structures that provide nourishment, relay information about the external environment, remove toxic wastes, provide communication and vital immune functions, all of utmost importance for skin health and beauty.

Glands of the skin

The skin has two main glands: the oil gland and the sweat gland. The oil gland secretes sebum and the sweat gland excretes water and trace minerals, such as salts and urea that are being eliminated from the body.

Oil gland (sebaceous gland) Originating in the dermis, the oil gland is attached to the side of the hair follicle. The gland produces sebum, an oily substance that is secreted onto the surface of the skin.

Sweat gland (sudoriferous gland) Originating in the dermis, the sweat gland produces a watery substance called sweat, onto the surface of the skin.

Oil production and skin congestion

As we have seen the oil gland is most commonly attached to the hair follicle, and produces oil. This oil makes its way to the surface of the skin via the pore. Pores become blocked with excess oil and dead skin cells, creating a pore blockage. These pore blockages are known as comedones.

The epidermis

The cell renewal process of the epidermis

Cells in the stratum basale reproduce themselves once approximately every 24 hours. The duplicate cell is pushed up into the stratum spinosum. Here they remain for about 2 weeks, working their way up to the stratum granulosum. Cells now transform into a waterproof substance called keratin. As they expel their water and oils into the intercellular fluid, they lose their nucleus and die. Ever moving upward, the cells will spend almost 2 weeks in the stratum corneum. The top layer of cells of the epidermis is constantly shedding. It consists of about 15-20 layers of dead, flat cells. It takes about 28 days for cells to reach the top layer of the epidermis. (Illustration: Structure of the epidermis)

griffin+row Exfoliate cloth gently but effectively removes dead skin cells from the surface of the skin. Regular exfoliation improves the appearance of the skin, and helps prevent pore blockages.

Melanin production in the Epidermis

Melanin is a brown pigment produced in the skin. It is produced in the basal layer of the epidermis, by specialised cells called melanocytes. The function of melanin is to protect the skin from the sun’s harmful radiation. Darker skin colours absorb less harmful UV radiation, so melanin is produced to darken the colour of the skin, and protect us.

Melanocytes are stimulated by UV radiation, to produce melanin. A suntan is actually the first sign of our skin being damaged from the sun.

Ideally, the melanin is distributed evenly throughout the layers of the epidermis, creating an even colour.

In this diagram, we see the melanocyte producing melanin that is concentrated in a small part of the epidermis, resulting in an age spot.

Age spots are common in mature skins that have been exposed to UV radiation during their lifetime. They are more frequent (and larger in size) in skins that have been exposed to air pollution.

Age spots can be prevented by proper cleansing of the skin, the application of products high in antioxidants, and avoiding exposure to the sun.

Chemistry in the epidermis (the acid mantle)

The acid mantle of the skin resides in the top layer of the epidermis, forming a protective barrier against the environment and transepidermal moisture loss (dehydration). The slightly acidic pH is formed as a result of combining oil and sweat from the glands, cells and intercellular fluid. The range of acidity for a healthy skin is between a pH of 4.5 and 6. It is the acidity which creates the ideal environment for all of the functions of a healthy epidermis.

Many things can affect the acidity of the epidermis, affecting the overall health of the skin. Most common offenders are foamy, alkaline cleansers and over-exfoliation. griffin+row Cleanse is a unique formulation that is gentle enough to emulsify oil, makeup and pollution without stripping the skin of its protective acid mantle. Cleanse rinses off completely, leaving the skin refreshed.

Natural moisturising factors (NMF’s)

Chemicals in the skin that collectively keep the skin hydrated are known as NMF’s. The three main NMFs build up in the spaces between the cells in the top layer of the epidermis. They’re formed as a by product of the keratinisation process, and support the skin by naturally binding moisture to the skin’s surface. Many of the same ingredients are used in moisturisers.

Hydration and NMF’s

Hydrated skin looks plump and bounces back when gently pinched. Hydrated skin absorbs the beneficial ingredients of the moisturiser, while resisting bacterial infection and spread of harmful microflora on the surface of the skin.

Dehydrated skin ages prematurely and doesn’t shed dead cells in a timely manner. Lines and wrinkles, such as those created during facial expression, remain on your skin longer. Dehydrated skin becomes prone to more serious skin conditions such as dermatitis, eczema and psoriasis.

griffin+row Hydrate contains ingredients similar to the NMFs lacking in your skin. With the replenishment of these NMFs, your skin is now able to optimally bind with the ingredients of your moisturiser, locking in moisture and preventing dehydration.

Read more about natural moisturising factors here.

Further reading