The pH value of the skin under normal circumstances

Only when the skin maintains a normal acid-base balance can it remain in the most perfect state and not easily develop acne or peeling. And when everyone chooses skin care products, they should also choose skin care products suitable for their skin according to the pH value of their skin. Therefore, many women go to cosmetics stores to test the pH value of their skin before buying skin care products. Under normal circumstances, what is the pH value of most people's skin?

The normal pH value of the skin surface is about 5.0-7.0, with an average of about 5.8, which is basically weakly acidic.

The role of the skin

1. Barrier function: On the one hand, the skin protects various organs and tissues in the body from the invasion of mechanical, physical, chemical and biological harmful factors in the external environment; on the other hand, it prevents the loss of various nutrients, electrolytes and water in the tissues. Therefore, the skin plays an important role in maintaining the stability of the body's internal environment. Without skin, it is unimaginable how the organs in our body would function.

2. Sensory function: Sensory nerves and motor nerves are distributed in the skin. Their nerve endings and special receptors are widely distributed in the epidermis, dermis and subcutaneous tissue. They sense stimuli and produce various sensations such as touch, cold, warmth, pain, pressure, itching, etc., causing corresponding nerve reflexes.

3. Regulating body temperature: Body temperature is a manifestation of heat generated during the metabolism of substances in the body, and is also one of the indispensable conditions for the body's cells to carry out various biochemical reactions and physiological activities. The skin is an important component of the body's heat dissipation. It can regulate body temperature through skin vasoconstriction, piloerection, reduced sweating, etc. It can also dissipate heat through physical methods such as radiation, convection, conduction, and evaporation.

4. Absorption: The skin has the ability to absorb external substances through the stratum corneum, sebaceous glands of hair follicles and sweat duct openings, which is called percutaneous absorption, penetration or penetration. It is indispensable for maintaining body health and is also the theoretical basis for modern dermatology topical drugs to treat skin diseases.

5. Secretion and excretion: The skin has certain secretion and excretion functions, which are mainly carried out through the sweat glands secreting sweat and the sebaceous glands excreting sebum. Sweating has the functions of dissipating heat and cooling down, protecting the skin, excreting drugs, and replacing some functions of the kidneys; sebum has the function of forming a lipid film on the skin surface and lubricating hair and skin.

6. Immune function: Both the epidermis and dermis of the skin contain cells involved in the immune response, such as keratinocytes, Langerhans cells, lymphocytes and macrophages. Keratinocytes secrete cytokines such as interleukin-1, interleukin-2, interleukin-3, and interleukin-6, which participate in the regulation of skin immune function and can activate target cells. Langerhans cells can bind to antigens and transmit antigen information to immune-active cells, initiating an immune response.

7. Metabolic effect: The skin, like other tissues and organs of the human body, has a common biochemical metabolic process. When the body's metabolism is impaired, it will also affect the normal metabolism of the skin, leading to the occurrence of disfiguring skin diseases. Conversely, when skin metabolism is impaired, it may also affect the metabolism of the entire body. For example, 7-deoxycholesterol in the epidermis can synthesize vitamin D3 after being exposed to ultraviolet rays. When problems occur in this metabolic process, it will affect the body's absorption of calcium and cause the occurrence of rickets.

Additional information:

Skin covers the entire body surface and is one of the largest organs in the human body, accounting for approximately 16% of body weight. The skin area of ​​an adult is approximately 1.2-2.0 square meters. The thickness of the skin varies throughout the body. It is thickest on the back, neck, palms and soles of the feet, and thinnest on the armpits and face. The average thickness is 0.5-4.0 mm. Although the thickness of the skin varies from place to place, it can be divided into two layers: the epidermis and the dermis, and is connected to the deep tissue through the subcutaneous tissue. Skin color varies depending on race, age, and health status.

There are dense grooves of various directions on the skin, which are called skin grooves. The diamond-shaped or polygonal raised parts of varying sizes between the skin grooves are called skin ridges, which form fingerprints on the fingertips. The fingerprint morphology is different between individuals, so fingerprints have individual differences. There are hairs of varying lengths and thicknesses on the skin. There are fingernails and toenails at the ends of the limbs. The skin can secrete sweat and sebum, which are secreted by sweat glands and sebaceous glands.