Epidermis: what it is, functions and structure

The skin is the largest organ in the body, but it’s easy to forget about it or take it for granted. When you’re learning about how to keep your baby’s skin healthy, you might want to know more about how the skin works.

The epidermis is the outermost layer of skin that forms our first line of protection from the outside world. We’ve put together this guide on what the epidermis is, its structure, its functions, the protection it provides and the conditions and disorders that can affect the epidermis, as well as how to look after it.

What is the epidermis?

The epidermis is the outermost layer of your skin. It’s the one you see when you look at yourself.

The epidermis is of varying thickness in different parts of the body. “High-traffic” areas that see a lot of use like the soles of your feet or the palms of your hands have a thicker epidermis than places like your eyelids, where it’s much thinner.

The anatomy of the skin with all three layers is:

The epidermis – the outermost protective layer that acts as a barrier against the outside world.
The dermis or dermal layer – the second layer which also protects your body from the world outside, contains touch receptors, sweat glands and hair follicles. It also helps to regulate temperature. Because there is no blood supply to the epidermis, the dermis also helps to supply it with nutrients and remove waste from it.
The hypodermis – Also known as the subcutaneous layer, the hypodermis is the bottom layer which helps to protect your body from harm, provides insulation, stores energy and connects your skin to muscle and bone.

Epidermis: structure

The epidermis itself is made of a further five layers. These are, in order, the stratum basal, stratum spinosum, stratum granulosum, stratum lucidum and finally the stratum corneum, which is the uppermost layer (the surface).

Stratum basal

Also known as stratum germinativum or the basal cell layer, the stratum basal is the deepest layer of the epidermis, is where new skin cells develop.

It also contains melanoctyes, which produce melanin. Melanin is a skin pigment that makes your hair, eyes and skin the colour that they are – the more melanin your body produces, the darker they will be. It also absorbs harmful UV rays to help protect your cells from sun damage.

Stratum spinosum

The stratum spinosum layer helps to make your skin strong and flexible.

Stratum granulosum

The stratum granulosum contains mature keratinocytes which produce large amounts of keratin precursors. Keratin forms hair, nails, and the skin’s outer layer.

Stratum lucidum

The stratum lucidum is a smooth, translucent layer of cells which provides a barrier to water. This layer is only found in the palms of your hands, your fingers and the soles of your feet.

Stratum corneum

The stratum corneum is the uppermost layer of the epidermis and is the one you can see. It helps to stop microbes getting into your body while ensuring the tissue beneath it does not dehydrate.

Epidermis: functions

The main function of the epidermis is to keep you protected. Your skin is part of your immune system as your first line of defence against illness, posing a physical barrier to potentially harmful pathogens. Your epidermis helps to keep these pathogens out (such as bacteria, viruses, parasites and fungi). It also works to protect you from harmful ultraviolet (UV) radiation from the sun and chemicals.

Not only is your epidermis a physical barrier against infection and disease, it also contains Langerhans cells. Langerhans cells are a kind of immune cell that decide which adaptive immune response to have to different foreign substances. They work to both recognise potentially harmful pathogens as well as ensuring the body does not provide an immune response unnecessarily.

The other functions of the epidermis are:

Hydration – The final layer of the epidermis (stratum corneum) helps to keep your skin healthy and hydrated by preventing water loss.
Making new skin cells - stratum basal, the bottom layer of the epidermis, is where new skin cells are produced.
Skin colour – Melanin is produced in the epidermis, which determines your skin colour.

Epidermis: conditions and disorders

As the body’s outmost skin layer, there are many different kinds of conditions, diseases and disorders that can affect the epidermis, some of which are more common than others.

Some conditions that can affect the epidermis are:

Acne – Often found on the face, back and chest, acne is a very common condition that affects most people at some point. It causes spots, oily skin and can sometimes cause your skin to be painful to touch.
Rosacea – A long-term skin condition that causes redness across the face, sometimes with a burning or stinging feeling when washing. It may also cause dry skin, swelling, or thickened skin after many years.
Dandruff – A common skin condition that effects the scalp, resulting in white or grey flakes of skin in the hair.
Eczema – Eczema is another common condition that causes the skin to be dry, itchy and red. It can be in small patches or all over the body, and it is very common in children.
Infection – Infections on the surface of the skin can be caused by bacteria, viruses, fungi or parasites. If you are concerned that you or your baby has a skin infection, you should speak to your doctor or pharmacist.

Epidermis: treatments

If you think that you or your child has a condition that’s affecting the epidermis, you can contact your pharmacist or doctor depending on the severity of the symptoms for further advice and treatment. Many skin conditions do not pose a long-term health risk and can be easily treated or managed.

It’s important to look after the epidermis to keep it healthy, and there are many factors that can inflame or irritate the epidermis.

A few ways you can look after your child’s skin are:

Use a mild, fragrance-free soap when bathing your baby. When bathing newborns (before 4 – 6 weeks) only use water, and don’t use any kind of soap at all.
Bathe your baby in lukewarm water, as hot water can dry out the skin.
Pat your baby dry with a soft towel instead of rubbing them down.
Try to avoid contract with triggers if they have an allergy. Allergies can often trigger skin conditions such as eczema or hives.
Apply sunscreen to your baby’s skin of at least 30 SPF when going outside in the summer. Babies who are younger than six months old should not be exposed to direct sunlight.

Remember, the skin is the largest organ, and it works all the time to keep us healthy. That means you should be taking care of it! Babies have particularly sensitive skin, so it’s important to look after it using gentle care to prevent irritation or inflammation.