Structure and chemical composition of the scalp

The epidermis or epithelial tissue is composed of 4 different types of cells, the most important of which, composed of keratinocytes, is distributed across many overlapping rows of cells divided into 5 layers: the basal layer, the spinous layer, the granular layer, the translucent layer (present only on the palm of the hand and the sole of the foot) and lastly the cornified layer. Keratinocytes are formed and reproduced in the deepest part (the basal layer), and from here, following the aging process, slowly climb towards the surface (in about 28 days), producing within them a protein called keratin, which has a particular resistance to external aggression (soap, oils, solvents, heat and cold, visible and ultraviolet radiation, germs, mold and pathogens, etc…).

The detachment of the now-dead cells from the surface is usually invisible. If, instead, for some reason, due to particular scalp problems, cellular masses form (hundreds or thousands of elements), the detachment becomes visible in the form of flakes (dandruff).
The basal layer is the only one that needs nourishment, which it receives from the underlying dermis. The epidermis is devoid of arterial or venous circulation. The basement membrane is a complex structure with an undulated shape that is responsible for both anchoring the epidermis to the dermis and for allowing and regulating the exchange of substances (nutrients and waste) between the epidermis and the dermis. In the dermis (connective tissue) the cells are scarcer and divided into various types: among these we can note the fibroblasts, mastocytes and macrophages. The most important are fibroblasts, that produce both the “fundamental” gelatinous substance, composed mostly of water, salt, sugar and protein, and various types of fibers (reticular, collagen and elastic), which take on the role of providing support, consistency and elasticity to the tissue itself. The dermis is full of blood vessels, lymphatic vessels, fibers and nerve endings. Finally, the hypodermis (subcutaneous adipose tissue) is composed mainly of interwoven fibrous bands (a direct continuation of those found in the dermis) that outline a series of spaces, called adipocytes, occupied by adipose cells. In the hypodermis there are fewer cells and nerve endings, while blood supply is more abundant. Under the hypodermis are bands of muscular tissue with the correspondent muscles.