What is sebum and what is its primary function?

Sebum is an oily substance produced by the sebaceous glands in the skin. Its primary function is to moisturize and protect the skin. The oiliness of sebum helps to keep the skin hydrated by preventing water loss, which is essential for maintaining skin elasticity and a healthy barrier function. Additionally, sebum contributes to the overall health of hair by keeping it moisturized and providing a natural shine. It also has antibacterial properties that help to protect the skin from bacteria and fungi.

The context of other choices reveals their significant role in skin care but does not align with the primary characteristics of sebum. While the waxy substance that protects hair is true in a certain context, it doesn’t capture sebum's broader moisturizing functions. Similarly, the statement regarding pH regulation describes other mechanisms within skin health rather than sebum. The mention of a protein aiding in skin healing is related to functions performed by different proteins like collagen rather than sebum itself. Hence, understanding sebum as a natural moisturizer highlights its crucial role in maintaining skin health.