The skin is an organ in the form of a flexible membrane covering the surface of the entire body. It provides protection and is in contact with the external environment. It resists mechanical, thermal and chemical aggression to a certain extent and has a broad variety of functions, such as metabolic, neurological and temperature regulation etc.
The skin is composed of three main layers:
The epidermis is the surface layer that protects our skin.
It is the first layer and forms an external barrier, providing the function of protection and waterproofing.
It is 500 microns thick on average but it can be as much as 5 mm thick on the soles of our feet.
The epidermis is composed of three main layers:
- the stratum corneum or horny layer
- the stratum germinativum or germinative layer
- the basement membrane
It is a malphigian epithelium structured in multiple layers which is keratinised and reduces skin permeability.
Keratinocytes are cells that are closely bonded to each other. They develop in the basement membrane and migrate towards the surface to form the intermediate germinative layer, terminating in the horny layer that seals the skin ’s surface. The horny layer is composed of keratin derived from dead keratinocytes.
The dermis is the living layer of the skin. It is a supporting connective tissue rich in fibres that makes the skin elastic and strong. The dermis contains the skin appendages.
The hypodermis is a fat cell sliding layer, performing transition and storage functions (water and fat). It is in close contact with the underlying layers.
The epidermis and dermis are clearly separated but are firmly anchored together by conical papillae, however, there is no clear definition between the dermis and the hypodermis.
