Final answer:
Cosmetology professionals are allowed to remove dead surface cells from the stratum corneum, the outermost layer of the skin, and to work on the hair shaft, which is the portion of hair visible above the skin. Both stratum corneum and hair shaft are composed of dead keratinocytes.
Step-by-step explanation:
Cosmetology professionals are trained and licensed to work on the hair, skin, nails, and other cosmetic concerns. When it comes to skin care, one of their responsibilities is the removal of dead surface cells. This is typically achieved through processes such as exfoliation and microdermabrasion. These processes target the stratum corneum, which is the outermost layer of the epidermis. The stratum corneum is composed of dead keratinocytes that have migrated from the lower layers of the skin. Over time, these cells are shed naturally, but cosmetic procedures can accelerate this process. It is important to note that cosmetologists are only permitted to work on the superficial layers of the skin, specifically the stratum corneum. Any procedures that affect deeper layers of the skin would require medical supervision.
Similarly, with hair, cosmetologists can work on the hair shaft, which is the part of the hair visible above the skin's surface. The hair shaft is made of dead cells and is considered an external surface. This is different from the hair root, which is the living part of the hair found within the hair follicle.
For sampling or treating, cosmetologists are strictly limited to the external parts of the skin, which are the stratum corneum of the epidermis and the hair shaft.