understanding your skin (part 1) - back to basics
Our skin is an organ of the body. When we think of organs of the body we think of the heart, liver, kidneys, lungs etc. We don’t initially think of the skin as an organ but in fact the skin is the largest organ of our body.
What is its function?
The skin’s main function is as a protective barrier for the body. It is the first line of defence against potential dangers such as toxins, microbes, bacteria, viruses and germs. It is when our skin is damaged or compromised that these particles are able to penetrate and cause havoc.
It’s also a protector of our body’s internal organs such as the heart, kidneys, liver, lungs, pancreas and the entire blood, nervous and bone systems. And of course our skin is water resistant. It protects our inside from water damage whilst allowing small particles and essential ingredients to penetrate.
What is the skin made up of?
The skin is made up of 3 main layers:
- The epidermis (outermost layer)
- The dermis (middle layer)
- The hypodermis / subcutaneous (innermost layer).
This is the very top layer of the skin, and is what you can see and feel. The epidermis is generally no thicker than a sheet of paper and within this contains 5 sub-layers.
From innermost to outermost sub-layer:
- Stratum Basale - the germinative layer
- Stratum Spinosum – spinous layer
- Stratum Granulosum – granular layer
- Stratum Lucidum – clear layer (only found in palms of hands and soles of the feet)
- Stratum Corneum – dead skin cell layer
Our skin cells begin their life in the Stratum Basale or germinative Layer. Here they are plump and well nourished. They continuously divide and create new cells. From there they move progressively through each sub-layer until they emerge as dead skin cells in the outermost sub-layer of the epidermis.
When your skin therapist talks about the 20-30 day cycle of cell turn over (new cells being made and the old dead skin cells falling off) they are talking exclusively about the sub-layers of the epidermis.
As the cells travel through each layer of the epidermis and move through their life cycle of approximately 20-30 days they start to become more dehydrated, flatten and begin to die. The dead skin cells then become the top layer of our epidermis. The dead cells are made up of dead keratin (a protein) that forms part of the skin’s protective barrier. They will naturally drop off or are removed via exfoliation products. We can shed approximately 30,000 - 40,000 skin cells per minute.
Removing dead skin cells helps to keep the skin fresh and clear. A build-up of dead skin cells can block the skin’s pores and prohibit moisturisers, boosters and treatment products from penetrating.
It is primarily the epidermis we are treating when we use skin care products. Most of the products designed today are able to penetrate and have an effect on the sub-layers, cells and fixtures of the epidermis and possibly the very top of the dermis.
The dermis is the second layer of the skin and this is where the blood vessels, oil glands, capillaries, nerve endings, specialised cells, hair follicles and sweat glands reside. It can also be referred to as the ‘true skin’ because of the amount of structures within the dermis.
Collagen and elastin fibres are found here. They are what keep our skin plump and tight. As we age, the collagen and elastin fibres shrink, and are not regenerated as quickly as in our youth. This is when we start to see more sagging, wrinkles and loss of tone on our skin.
The dermal area also holds the receptors for pain, touch and pressure.
the hypodermis (subcutaneous)
This is the innermost layer of skin that sits on top of muscle. Its main purpose is to attach the skin to the underlying bone and muscle. It also acts as a cushion for the epidermis and dermis layers of the skin. There are some blood vessels and specialised cells such as fibroblasts that make collagen and elastin fibres that are retained in the dermis.
This layer generally contains about 50% fat tissue. Fat cells called adipocytes are made here. They are what provide not only the cushioning but also heat insulation for our body.
Coming soon: part 2 – the functions of the 3 layers