Skin Explained - Definition, Structure & Function
What do you know about your skin? You have to understand your skin to identify and prevent skin or hair problems if they arise.
And to fight myths about dark skin that spread in black communities.
Many people skip the science behind the skin and move directly into creating skincare routines, but it is a mistake to ignore the facts and blindly follow advice on the internet.
To get the skin you always dreamed of you have to get acquainted with the skin you’re in.
This article will help you understand the skin’s structure and functions so you can fully understand the nature of your skin and create a routine that is effective.
For your convenience, you can find all external references used to write this post here.
Let’s have a look beyond the surface.
What is Skin?
There is a barrier that separates you from your environment – your skin.
Skin is the outer covering of the body.
It is the largest organ you have composing the integumentary system along with its appendices.
Dark skin is defined as skin that contains high amounts of melanin pigments.
Your skin takes on different thicknesses, colours, and textures all over your body.
That will influence how to apply products in your routine.
Your eyelids have thin and delicate skin, while the soles of your feet and the palms of your hands are thicker and harder.
Thinner areas of the skin require less strenght and more care.
Thicker areas of the skin like the palm of your feet may require specialized treatment like frequent dead skin removal.
The thickness of your skin also depends on age and sex: Older people generally have thinner skin than younger people, and men generally have thicker skin than women.
Also, your head contains more hair follicles than anywhere else. But the soles of your feet have none.
Functions of the skin
Skin does not exist solely for cosmetic value. You should aim to have healthy skin first. And aesthetically pleasing skin, second.
Skin is one of the most versatile organs.
It is a stable but flexible barrier with 3 main roles: Protection, Regulation and Sensation. Different functions include:
- Waterproofing the entire body;
- The first line of defence against bacteria and other microorganisms;
- Protective barrier against mechanical, thermal and physical injury and hazardous substances;
- Regulation of body temperature (ex: cooling via sweat);
- A sensory organ that gives information about pain, pleasure, temperature and pressure;
- Reduction of harmful effects of UV radiation;
- Production of vitamin D.
Structure of the skin
It’s important to know the skin’s structure to understand which products penetrate the skin, and which products work only on the skin’s surface.
The skin is not a sponge and it doesn’t absorb all product you apply.
Skin absorption and skin penetration are 2 different concepts.
Skin absorption = product applied enters the blood stream.
Skin penetration = product applied enters the skin into the deep layers.
For skincare products skin penetration is what we are looking for. The products applied to the skin stay in the targeted skin layer and do their job.
The skin is composed of 3 layers as seen in the figure below. They are the Epidermis, the Dermis and the Hypodermis (subcutaneous fat layer). Each layer has its functions.
The Epidermis
The skin you can see, and where you apply your products is called the epidermis. And it is the outermost layer of skin.
Its prime function is to act as a physical and biological barrier to the external environment, preventing the entrance of irritants and allergens.
At the same time, it prevents the loss of water. The epidermis itself is composed of layers organized in several ‘sheets’ of cells.
They are 95% made up of cells that produce keratin – keratinocytes. Most body parts have four layers, but those with the thickest skin have five.
The epidermis constantly renews itself: new cells are made in the lower layers of the epidermis and within four weeks these cells are gradually pushed to the surface of the skin by newer cells, where they harden and then eventually die off.
This constant renewal – desquamation process – serves to replace the cells that are lost and fall to the ground as tiny flakes when you rub the skin.
The cells in the epidermis grow faster in response to pressure or rubbing (for example exfoliation). The amount of skin flakes that are shed remains the same, though.
The epidermis also contains other types of cells with special functions:
- Melanocytes produce and store the pigment called melanin that gives skin its colour.
Although everyone has the same number of melanocytes, dark skin people have melanocytes that produce higher amounts of melanin.
The amount of melanin differs from person to person, but the darker the skin, the more melanin contains.
The main function of melanin is to absorb ultraviolet (UV) radiation to protect us from its harmful effects.
These cells produce more melanin when your skin is exposed to sunlight – which is why it becomes darker – to protect the skin from the sun’s harmful UV rays.
- Lymphocytes and Langerhans cells play an important role in fighting germs.
- Merkel cells are special nerve cells in the skin that enable you to sense pressure. For example, these cells are present in the fingertips and give you the sense of touch.
The Dermis
Located between the epidermis and the hypodermis is the dermis – the inner layer of the skin.
The primary role of this layer is to sustain and support the epidermis.
It also protects by cushioning the deeper structures from physical injury and plays an important role in wound healing.
This layer is made up of Elastin (elastic fibres) and Collagen (protein fibres). They are responsible for giving skin flexibility and strength, respectively.
Collagen makes up 70% of the dermis and is continually broken down and replaced; Elastin fibres give the skin its elasticity.
However, both are affected by increasing age and exposure to UV radiation, which results in sagging and stretching of the skin as the person gets older and/or is exposed to greater amounts of UV radiation.
The Hypodermis
The hypodermis or subcutaneous layer is the bottom layer of the skin.
It consists largely of fat and connective tissue, providing structural support for the skin.
As well as, protecting the body from cold and physical aggressions. It is on this layer that you can find blood vessels and nerves.
Although the hypodermis layer is not visible, it has an important role in the appearance of the skin.
As you get older, your hypodermis decreases in size and you lose subcutaneous fat causing your skin to sag.
The different layers of your skin affect your appearance in different ways.
Any skincare product must be applied with responsibility paying attention first to your health and only then taking into consideration cosmetic value.
Being the largest organ in your body, your skin requires care.
In order to keep this barrier healthy, you need to understand what the word skincare means and with what objective you should create one.
Fortunately I have a post to help you. Read below.
Skincare is the care and keeping of the largest organ in your body — your skin! The etymological definition – Skin + Care stands for “caring for your skin”.
Disclaimer: This article is informational only. This article does not provide medical advice, diagnosis, or treatment. Any information published on this website or by this brand is not intended as a substitute for medical advice, and you should not take any action before consulting with a healthcare professional.
Read The Other Articles of The Series.
Skincare is the care and keeping of the largest organ in your body — your skin! The etymological definition – Skin + Care stands for “caring for your skin”.
This article will help you understand the value of caring for your complexion and present six reasons why skincare is essential for everyone.
The steps for healthy skin are easy to implement. The three basic steps of a skin-care routine are Cleansing, Moisturizing and Protecting.
