Skin anatomy diagram
The skin is composed of 3 main layers, from superficial to deep:
Epidermis| Dermis| Subcutaneous layer or hypodermis
Between the epidermis and the dermis lies the basal membrane or dermo-epidermal junction. This area is important as it can be affected in some bullous (or blistering) skin diseases.
This is the outermost layer of the skin, and is composed of cells called keratinocytes because they produce a type of protein called keratin. These cells maturate and progress from the deepest layers of the epidermis to the surface, and continuously shed off.
We are usually unaware of our skin shading off but certain disorders can affect keratinocytes or their maturation process (eczema, psoriasis and other scaly skin diseases).
The epidermis doesn’t have any blood vessels.
Its main function is to act as the protective barrier of the skin. It varies in thickness from the soles of the feet (1.5mm) to the eyelids (0.05mm).
The dermis is the tough and flexible layer that lies below the epidermis. Its main components are collagen and elastin and it’s responsible for the firmness, elasticity and texture of the skin.
It contains blood and lymphatic vessels, sweat and sebaceous glands, sensory nerve endings and hair follicles.
One of its main functions is immunological, by producing different types of cells and complexes that help us fight infection and also aid healing of wounds.
If a wound reaches the dermis, it will produce a scar.
Subcutaneous layer or hypodermis
This layer connects the overlying dermis to the underlying organs and other structures. It’s composed of connective tissue, fat cells and blood vessels, and it tends to be thicker in females than males.
Its functions include cushioning, temperature regulation and insulation.