Milady Cosmetology Practice Exam 2025 – All-in-One Guide to Master Your Cosmetology Certification!

The principal functions of the skin include several key roles beyond protection, sensation, heat regulation, and excretion. Among these additional functions, secretion and absorption are crucial.

Secretion refers to the process by which the skin releases substances necessary for maintaining its health and function. This includes the secretion of sebum, an oil produced by sebaceous glands that helps to keep the skin moisturized and protects it from external elements like bacteria and pollutants.

Absorption is another essential function of the skin, allowing it to take in certain substances. The skin can absorb topical applications of creams, lotions, and medications, which can then penetrate the skin barrier and exert their effects. This function enables the skin to play an active role in health treatments and cosmetic applications.

The other options, while they involve skin or body functions, do not pertain directly to the core principal functions of the skin as defined in the context of dermatology and cosmetology. For example, filtration and respiration primarily pertain to the lungs and blood systems, while elimination may refer more broadly to bodily processes and rejuvenation and growth focus on changes in tissues and cellular processes rather than direct functions of the skin.