Which two secretions are responsible for producing the acid mantle of the skin?

The acid mantle of the skin is primarily formed by the combination of sweat and sebum. Sweat, which is produced by sweat glands, contains water and electrolytes, while sebum, secreted by sebaceous glands, is an oily substance that helps to moisturize the skin. When these two secretions mix, they create a thin layer on the skin's surface that has a slightly acidic pH.

The acidity of the acid mantle is crucial for several reasons. It helps to protect the skin from pathogens and harmful bacteria, as many microorganisms thrive in neutral or alkaline environments but struggle to survive in acidic conditions. This protective barrier also assists in maintaining hydration by rendering the skin less permeable to water loss.

In contrast, other combinations listed do not contribute to the formation of the acid mantle. For example, keratin and melanin are important components of the skin but do not function in creating the acid mantle. Keratin provides structural strength and melanin offers pigmentation and UV protection. Similarly, pus and mucus are associated with infection and inflammatory responses rather than normal skin function. Thus, sweat and sebum are the correct secretions responsible for generating the skin's acid mantle and maintaining its overall health and protective qualities.