The epidermis is divided into five layers: stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and dermis. The stratum corneum is the outermost part of the epidermis, formed by the continuous division and evolution of keratinocytes, forming a strong and elastic layer. So, to which structural level does the skin belong? Let’s find out below.

To which structural level does the skin belong?

The skin is an organ of the body, composed of many tissues such as epithelial tissue and underlying connective tissue, nervous tissue. These tissues are orderly arranged and integrated to form a skin organ with various functions, which is a very safe natural protective barrier of the body, capable of resisting various pathogens. In addition, it has the functions of sweating, excretion, and heat dissipation. Once the skin is damaged, it is prone to various diseases, such as infection causing inflammatory changes in the skin, allergic reactions causing urticarial changes, eating too much greasy food causing excessive sebaceous gland secretion, and atypical hyperplasia of skin tissue cells causing pathological changes of skin cancer. Pay attention to the care of the skin in daily life to prevent the occurrence of skin diseases.

What are the layers of the skin?

The outermost layer of the epidermis, the stratum corneum, is thin and keratinized, also known as callus cells, consisting of 6-10 layers. It has protective functions, preventing water loss and also preventing the invasion of bacteria and harmful substances. A healthy stratum corneum should not be too thick or too thin. A too thin stratum corneum cannot resist external stimuli, making the skin very sensitive and prone to water loss. A too thick stratum corneum makes the skin lose its luster, become rough and dull, and also blocks the absorption of nutrients from skincare products.

The second layer, the stratum lucidum, controls skin moisture, preventing excessive water loss and intake. This layer is absent on the face and only present on the palm of the hands and soles of the feet.

The third layer, the stratum granulosum, prevents foreign invaders and filters out other substances.

The fourth layer, the stratum spinosum, contains a lot of water and nutrients, and has the ability to divide and reproduce cells, maintaining the extensibility of the epidermis.

The fifth layer consists of thin keratinocytes and pigment cells. Keratinocytes can continuously degrade to form neonatal somatic cells, changing the original somatic cells upwards to maintain the basic metabolism of the epidermis. Pigmented somatic cells cause pigmentation and maintain the dermal layer. The amount and size of pigment determine the skin tone. In addition, direct sunlight can cause a large amount of pigment formation.