Anatomy of the Skin

The skin is the largest organ in the body and it consists of three main anatomical components: the Epidermis which is the top layer of the skin, the Dermis which is a deeper layer and below that the subcutaneous fat layer.

Epidermis

The epidermis mainly consists of keratinocytes which start their lives at the basal layer of the epidermis and work their way to the surface. This process on average, in the normal person, takes 28 days. Therefore, the top layer is continually shedding itself. At the basal layer of the epidermis, melanocytes or pigment cells that contain melanosomes act as our body’s natural sunscreen. People with darker skin will have larger and more numerous melanosomes. At the base of the epidermis are Langerhans cells which form part of our immune system that are able to fight foreign micro-organisms such as bacteria, viruses and fungi. The top layer of the epidermis is called the stratum corneum and this consists of dead cells called corneocytes and these cells are glued together by fats or lipids. The stratum corneum performs a very important physical, water-proof barrier function and disruption of this physical barrier can lead to eczema and/or infection and sensitivity.

Dermis

The dermis is the thickest layer of the skin and lies between the epidermis and the subcutaneous fat layer. It contains cells called fibroblasts which produce collagen, elastic fibres and a gel-like ground substance which is composed of mucopolysaccharides, primarily hyaluronic acid, chondroitin sulphates and glycoproteins. The collagen and elastic fibres and the ground substance provide strength, firmness, support and elasticity to the skin. The dermis also contains hair follicles, oil glands, sweat glands and blood vessels. The blood vessels in the dermis supply nutrients both to the dermis and the epidermis.

With the natural ageing process and with chronic sun damage there will be changes to both the epidermis and the dermis.

Cosmeceutical topical preparations with active ingredients work on a cellular level and are designed to help reverse or slow down the normal ageing process and/or photo-ageing. Fortunately, most of these products have been designed to work on both the epidermis and in the dermis e.g. a product that helps to restore the normal, healthy barrier function of the epidermis while also helping to reverse some of the damage in the dermis by stimulating new collagen, elastic fibres as well the ground substance i.e. hyaluronic acid.

Sub-Cutaneous Fat

The subcutaneous fat layer (hypodermis) is made up of fat and connective tissue. It acts as a cushion and supports the overlying dermis and epidermis.

We are often asked what the difference is between the epidermis and the dermis so we have highlighted these two important layers, but some many other layers and components make up the largest organ of the body.  When it comes to buying cosmeceutical products most of the active ingredients work in these layers and that is why it is important to know and understand the difference.