What is keratin_What does keratin look like

Exfoliation is a skin care task that many girls do nowadays, but not everyone understands what exfoliation is. In terms of its role in the human body's surface skin, on the one hand it can protect the skin from being damaged by ultraviolet rays in the sun, but on the other hand, a too thick stratum corneum will prevent the skin from absorbing the moisturizing ingredients in skin care products. There is no way to distinguish the cuticle from the appearance.

What is keratin?

Cutin is the main component of plant cuticle. It is not a single substance, but a polymer of highly unsaturated higher fatty acids (hydroxy C18 fatty acids). The composition of cutin can vary greatly depending on the type of plant. Cutin is the skeleton material of the cuticle and generally exists in layers on the surface of stems and leaves. In addition, it also exists in free surfaces such as mesophyll cells that are in contact with air within the tissue. The cuticle covering the outside of the stratum corneum has a high degree of oxidative polymerization and is infiltrated with a considerable amount of wax. In contrast, the arrangement direction of the molecules within the layer shows obvious polarity. Certain parts with this polarity can combine with water through hydrogen bonds, while non-polar carbon-hydrogen chains can only absorb water through very weak van der Waals forces. This has an impact on the surface of the cuticle, that is, the contact angle of water droplets attached to the plant surface.

What does keratin look like?

The keratin is not easily visible in the skin. It is about the same color as the skin and feels bumpy to the touch. Generally, people are more likely to grow obvious keratin when they are over 30 years old. It will appear earlier if the skin quality is poor and later if the skin quality is good. Under the electron microscope, the stratum corneum cells are filled with densely packed parallel keratin tension filaments immersed in amorphous substances, mainly histidine-rich proteins contained in transparent keratin.

The protective function of keratin

(1) Prevention against electricity. The stratum corneum is a poor conductor of electricity and has a certain impedance to low voltage current. The resistance value is affected by factors such as the skin, sweat gland secretion and excretion activities, mental state and climate. It is particularly related to the water content of the stratum corneum and its surface humidity. The resistance value is inversely proportional to the amount of water, that is, the resistance value to the skin is greater when it is dry than when it is wet, and the conductivity is lower. Therefore, if the stratum corneum is artificially removed, the tissue below the stratum corneum will become a conductor of electricity, directly causing electric shock.

(2) Ability to absorb light. Most of the UV rays are absorbed by the epidermis to protect the body's organs and tissues from damage by the sun. Artificially removing the stratum corneum will inevitably expose the skin tissue to the sun without any cover.

(3) Protection against mechanical damage. According to tests, it takes 0.04 Newtons of force to tear the human stratum corneum to 2 mm wide. If the stratum corneum is dehydrated, only 0.01 Newton of force is needed

(4) Protection against chemical damage. The cytoplasm, cell membrane and intercellular spaces of keratinocytes in the stratum corneum all act as barriers to chemical substances. The surface of normal skin is slightly acidic, with a pH of 5.5-7.0. Therefore, the skin has a certain ability to neutralize acids and alkalis.