The skin is the largest organ in the human body and accounts for up to one-sixth of our body weight. The skin acts as a barrier between the human body and its environment and fulfills a large number of tasks essential for maintaining human health.

The skin consists of three layers: epidermis, dermis, and hypodermis. Average skin thickness is 4 mm.
The primary cell populations of the epidermis are creatinocytes (86%), melanocytes (9) the epidermis consists of four layers. The epidermis layers consist of (in order from outer to inner):

– The Stratum Corneum layer consists of the cells without nuclei and any important biological function. As the cells have no nuclei, they can withstand pH. This level of acidity protects against bacteria that are present in the environment.
– The Stratum Granulosum layer is composed of melanin and keratin granules.
– The Stratum Spinosum layer is made up of keratinocytes that have ligaments that strengthen the bond between the cells.
– The Stratum Basale layer – the layer that creates new cells and thus ensures a permanent regeneration of the epidermis. Among the cells in this layer are melanocytes (at a ratio of 1:10 to keratinocytes). The slowing down of skin regeneration begins at the age of 25. When this occurs, it is time to start using AHA (occasionally to perform a peeling treatment based on glycolic acid in clinic, and to use lactic acid at home). At an older age the slowdown becomes more significant, and in addition to AHA acids it is recommended to use Retinoids.

The pH of the epidermis:
The skin is wrapped in an acid envelope Marchionni. The pH of normal skin is 5.5. The acidity of the skin can worsen due to skin diseases. For example, in cases of seborrhea the acidity of the skin is 6; in cases of eczema and acne, – 7.0. Therefore, in these cases, it is very important to use substances that contain acids.

The dermis is divided into two parts: the papillary dermis and the retinal dermis.
The papillary dermis has a network of capillaries, and the reticular dermis contains:
– Collagen fibers – give support to the tissues
– Elastin fibers – responsible for flexibility
– Glycosaminoglycans – polysaccharides – large molecules that are able to absorb water.

Fibroblasts (the main cells in the dermis) are intertwined. The combination of collagen, elastin, and Glycosaminoglycans creates extra extracellular matrix (ECM).
The dermis is regenerated regularly by the decomposition of ECM components and renewal.

In addition, within the dermis, there are epithelial structures, called skin follicles, which are deep in the dermis. These structures are divided into:
– Hair follicles
– Sebaceous glands
– Sweat glands

The sebaceous glands and sweat glands secrete substances that are transferred to the surface of the skin by channels. These substances help prevent moisture loss, create an acidic environment on the skin surface, and regulate body temperature.
It’s important to understand for acne treatment that the Sebaceous glands are epithelial structures. Therefore, it’s crucial to use AHA/AHB acids.

The nervous system consists of nerve fibers in the dermis layer, and receptors, most of which are present in the epidermis layer.
The nervous system is responsible for the sense of touch, the sense of pain, temperature sensing, and the acidity of the environment. The information is transmitted by sensory cells to the brain.
The sense of touch is generated by cells of the following types: Pacinian corpuscles, Golgi-Mazzoni corpuscles, and Meissner corpuscles.
A sense of cold is generated by end-bulbs of Krause.

The sensation of pain is generated by receptors of A-Delta Nerves and Type C Nociceptors. Type C Nociceptors are involved in the development of neurogenic inflammation in the skin following the use of peels.

Noon Aesthetics has a patent pending method that prevents the development of neurogenic inflammation due to the use of acids and allows acids usage at high concentrations without causing irritation.

Blood vessels are found only in the dermis layer. Through the capillary network in the capillary dermis, plasma emerges from the blood vessels in the form of diffusion. This plasma contains water and all other substances required for normal functioning of the skin cells. Skin cells receive water only through blood vessels. Getting water from the environment is not possible. The blood-vascular system is responsible for:

– Supply of oxygen and essential substances to the function of cells
– Waste disposal
– Temperature regulation
– Healing of wounds

The hypodermis consists of fat cells (adipocytes) that store fat, which serves as an energy source.

Main groups of skin diseases and problems:

  1. Infectious diseases:

–  Bacterial diseases
–  Viral diseases (For example: herpes, viral warts)
–  Fungal diseases
– Parasitic diseases, for example: scabies

  1. Diseases of the hair follicles and the sebaceous glands, for example: acne vulgaris, seborrhea, rosacea.
  2. Autoimmune diseases (collagen diseases), for example: lupus, scleroderma
  3. Inflammatory diseases:

– Contact Dermatitis
– Atopic Dermatitis

  1. Reactive rashes( For example: rash due to use of medications or cosmetic product)
  2. Photodermatoses( For example: photosensitivity, phototoxicity, photorealogy)
  3. Moles and benign skin lesions
  4. Malignant skin tumors


We will define a number of problems we may encounter:

  • Hyperkeratosis is the thickening of the corneal layer by the proliferation of normal cells without a nucleus
  • Pararekatosis is epidermal thickening by multiplying cells with a nucleus (interference in the keratosis of keratinocytes). Pararekatosis is divided into two types:
  1. Psoriasis (due to inflammation)
  2. Solar Keratosis (due to skin growths)