Skin structure
The skin is the largest organ of your body and holds many important functions. It has an area of roughly 2 m² and represents 15% of your body weight.
Source: Richardson, Understanding the structure and function of the skin, Nursing Times (2003) ↗Skin layers
Select a layer to see its position and role.
Epidermis
The epidermis is the external layer of the skin with a thickness of 0.07 to 1.4 mm. It has two main layers: the living basal layer at the bottom close to the dermis, and the outer layer called stratum corneum. The cells of the basal layer divide and continually push older cells towards the skin surface. This perpetual process transforms the round, nucleated cells of the basal layer into flattened, keratin-rich ones found in the stratum corneum. During this process the cells eventually die; those dead cells make up the biggest part of the epidermis. Once they reach the outermost part of the skin they eventually shed. The epidermis itself has no blood supply and depends on diffusion from the underlying dermis for its metabolic needs. The dead-cell layer of the stratum corneum protects the skin from water loss.
Dermis
The dermis lies underneath the epidermis and acts as a support to the upper layer. This thicker layer of the skin consists of collagen and elastin fibres, which are supplied by a rich network of small blood vessels. Dermal elastin makes the elastic white collagen give the skin its strength. Specialised skin structures such as hair follicles, sebaceous and sweat glands are also found in the dermis. Nerves that extend through the dermis are sensitive to heat, cold, pain, and pressure.
Hypodermis
The dermis is connected to the underlying loose tissue called hypodermis. This layer consists of various amounts of adipocytes (fat cells) which store fat in our body. The amount of fat in our skin represents between 15% and 30% of the total body mass. This big variation in numbers can be explained by the different amount of fat tissue of men and women. The latter generally have more adipose tissue than men.
The main functions of the skin
Protection
It acts as a barrier and protects us from bacteria, viruses and fungi.
Sensation
Sensory receptors (nerves) react to external stimuli.
Metabolic Activity
It absorbs different things such as lotions, creams and UV light from sun which generates vitamin D. It also has a detoxifying function as the body can eliminate products through the sweat.
Thermoregulation
It regulates the body temperature.
