The skin is composed of the epidermis and the dermis. The epidermis is an important part of the skin and is where much of the pathology of skin conditions including skin cancer resides.
The Basal Layer of the epidermis
The Basal layer where the stem cells sit and where new skin cells are made. Once the new skin cells are created they divide and rise up the levels of the epidermis. During division abnormalities can occur. Langerhans cells are the natural surveyors of the immune system and will generally mop up any abnormalities in DNA that are made during the replication period.
The epidermis and the ‘horny layer’
The horny layer (yep get excited!). Skin cells start in the bottom layer of the epidermis and over 19-21 days gradually work their way up to the top layer of the skin to naturally renew themselves. Once at the top of the epidermis they lose most of their features become thick and flat and then eventually don’t stick to other cells and slough off and be shed (this is what we see as dry flaky skin)
Before it sheds, this top layer provides a natural waterproofing layer – preventing water loss and allows permeability of the skin. It contains lipids but is very thin. .01-/.02mm so easily sensitive and damaged with external influences such as abrasive detergents, pollution weather etc.
Damage to this layer with these harsh abrasives can lead to an increase the loss of moisture and in turn dry scaly skin.
So you can see that our protection from the outside world is extremely thin. We need to keep as healthy as possible, hence things like microdermabrasion and harsh exfoliators that abrade it make no sense at all! Why would we weaken the .01mm skin defence!
The dermis contains hair follicles and sweat glands that are derived from the epidermis which creates a reservoir of regeneration should the epidermis be lost via injury or burns. So basically we need the dermis to make new skin.
Collagen and elastin are the main constituents of the dermis and are surrounded by Hyaluronic Acid.
Fibroblasts are cells that lie in the fluid dermis and produce proteins such as hyaluronic acid, which holds water and maintains the plumpness of the skin. Fibroblasts are the only permanent living cells – they produce fibres and chemicals and are the only way to preserve youthful skin is to generate these.
Fibroblasts protect collagen by inhibiting collagenase and at the same time producing pro-collagenase that degrades old collagen that needs to be replaced..
So you see most of what we need to be youthful sits in the dermis.
What is the dermis?
The dermis is the layer of skin that lies beneath the epidermis (first layer) and above the subcutaneous layer (hypodermis or fatty layer). It is made up of fibrous and elastic tissue, which gives the skin strength and flexibility (also keeps our skin looking young).
The inner layer of skin (dermis) contains blood vessels, sweat glands, hair follicles, and other structures. It is made up of a thin upper layer called the papillary dermis, and a thick lower layer called the reticular dermis.
Dermis vs epidermis
Dermis and epidermis can be thought of as the body's outermost layers of protection.
Dermis resides below epidermis and is made up of living cells, whereas epidermis is the outermost part of the body that helps protect against dehydration, trauma, and infection.
Dermis is a type of tissue that contains blood vessels, while epidermis does not. In our bodies, the dermis is made up of dense irregular connective tissue (meaning the tissue that provides structure and helps skin hold its shape isn’t formed into a pattern). The epidermis however, is made up with layers of perfectly flattened cells.
What is the function of the dermis?
The dermis is a protective threadlike structure that includes collagen, elastic tissue, blood vessels, nerve endings, hair follicles, and sweat glands. The dermis supports and protects the skin and deeper layers, assists in thermoregulation, and aids in sensation.
Elastic tissue found in the dermis helps support the skin and provides flexibility. Nutrients via blood support the epidermis, hair follicles, and sweat glands. The blood supply also helps trigger the body’s immune response when the skin is broken by allowing white blood cells, and other cells to pass.
The dermal blood supply also plays a role in temperature regulation. Several pressure receptors are found in the dermal layer of skin. These nerve endings are sensitive to changes in pressure and temperature and help the body to sense if it is too hot or too cold. The small blood vessels (capillaries) can tighten to help keep us warm or relax to help keep us cool. This is why we go pale when it's cold and flushed when it's hot.
How many layers of the skin are there?
The skin is made up of three primary layers: the epidermis, dermis, and hypodermis. The epidermis is the outermost layer of skin and provides a waterproof barrier that helps protect our bodies from the elements.
It functions as a barrier to keep harmful bacteria and germs from entering your bloodstream and causing infection. The epidermis also helps to shield your body from the harsh elements like rain, sun, and wind. In addition, this layer of skin is continually regenerating itself. Every day, your body sheds approximately 40,000 old skin cells which are replaced by new ones.
So, in essence, you have brand new skin every 30 days! Finally, the epidermis houses Langerhans cells which play an important role in the immune system by helping to fight off infection-causing germs.
The epidermis, or the outermost layer of skin, contains melanin. This is the pigment that provides colour to skin, hair and eyes. The concentration of melanin in your epidermis determines the darkness of your complexion. Those who produce higher levels of melanin generally have darker skin and may tan more rapidly.
The dermis is located beneath the epidermis and contains collagen and elastin fibers that give our skin strength and elasticity. It also facilitates hair growth, some sensations such as pain and temperature, oil and sweat production and a blood supply to the epidermis.
The hypodermis, or subcutaneous tissue, is the bottom layer of skin that consists of fat and connective tissue. It functions as a barrier to keep harmful bacteria and germs from entering your bloodstream and causing infection. It also protects our muscles and bones, connects our skin to our muscles has a nerve and blood supply that helps to regulate body temp.
5 layers of the skin
The first five layers of the skin are what's known as the epidermis. It's made up of different cells that work together to protect your body. The epidermis is important because it helps keep harmful things out of your body and it also helps to regulate your body temperature.
1. Stratum corneum
The first layer of skin that helps protect the body from the environment. It is made up of keratin and other materials that help keep bacteria and UV damage at bay. This layer also helps keep moisture from escaping, which helps the skin stay hydrated.
2. Stratum lucidum
A clear, thin layer of skin that helps protect against damage. It is found on the palms of the hands and soles of the feet, which are areas that commonly experience friction. By having this layer of skin, the body is better able to withstand damage caused by friction.
3. Stratum granulosum
The stratum granulosa is a layer of cells that helps to form a waterproof barrier. This barrier prevents fluid loss from the body, which is an important function.
4. Stratum spinosum
The stratum spinosum is a layer of skin that helps to make it flexible and strong. This is important because it helps to protect your body from injury and keeps your skin looking healthy. This layer also contains dendritic cells, which are part of the body’s immune system that helps fight against foreign invaders such as germs.
5. Stratum basale
The deepest layer acts as a water barrier by producing lipids/ oil (which repel water). It also stimulates the production of melanin and converts UVB into Vitamin D. It is also responsible for replacing dead or damaged skin cells.
What are the 7 layers of skin?
The 7 layers of the skin include the five layers of epidermis listed above and two layers of the dermis.
6. The papillary layer
Is the uppermost layer of the dermis. It's thinner than the reticular layer and is composed of loose connective tissue. It also attaches the epidermis to the dermis and is where our fingerprints come from.
7. The reticular layer
Is the deeper, thicker layer of skin that consists of dense connective tissue and bundles of collagen fibers. It is less cellular than the superficial layer and provides support and structure to the skin.
How many layers of skin does it take to bleed?
The dermis is the layer of skin that contains blood vessels, so when that layer is cut, the vessels are also cut and bleed.
Stay tuned for what happens next! (ie skin care and treatments that create a youthful glow!)