Skin

With a surface area of 1.5-2 m², the skin is the largest organ of the body. It consists of three layers: the epidermis, the dermis, and the subcutaneous connective tissue, each with its own distinct function.

The skin is a versatile and indispensable organ. It protects the body against harmful external influences such as pathogens, sun rays, and dehydration, and enables us to feel temperature and pain.

Epidermis: The top layer of the skin is the epidermis. This is the visible part of the skin and is in most places only a few tenths of a millimetre thick. This layer protects the body against harmful external influences, such as dehydration, sunlight, and the penetration of dangerous (liquid) substances. Bacteria, fungi, and viruses are also kept out in this way. The epidermis renews itself continuously, a process that is faster in young people than in older people and ensures that a wound closes again fairly quickly. The epidermis itself consists of two different layers: the horn layer, which mainly contains dead skin cells that protect the body (and is extra thick in places with a lot of callus, such as the soles of the feet and the palms of the hands), and the germinative layer, where new skin cells are produced that slowly move towards the surface. The pigment cells, which determine how dark the skin is and protect against sunlight, are also located in this layer.

Dermis: The middle layer is formed by the dermis, a 1-3 mm thick layer of connective tissue that provides the strength and elasticity of the skin. The older the skin, the less stretchable and strong it is. In the dermis lie the so-called skin appendages, such as sebaceous glands (not on the palms and soles), sweat glands, small lymph vessels, hair roots, and the nail bed. In addition, small blood vessels and nerves are found here, ensuring that the skin is well perfused and providing sensation (touch, temperature, and pain) at that spot.

Subcutaneous connective tissue: The deepest skin layer is the subcutaneous connective tissue. This layer consists mainly of fatty tissue interwoven with connective tissue and provides protection for the underlying organs and body parts. In addition, fat is an important storage place for energy, serves as an insulating layer, and thus plays a role in maintaining body temperature.