What is the role of sebaceous glands?

Sebaceous glands play a crucial role in maintaining skin health through the secretion of oil, specifically sebum. This oily substance serves multiple functions: it lubricates the skin and hair, preventing dryness and brittleness while providing a barrier against external environmental factors such as bacteria and fungi. The oiliness created by sebum helps to keep the skin moisturized and plays a role in the skin's overall appearance. Additionally, this protective layer can help to prevent transepidermal water loss, thus aiding in hydration. The secretion process is typically stimulated by hormones, particularly during puberty, which is why sebaceous glands become more active during this time.

In contrast, the other options involve processes not associated with sebaceous glands. For instance, insulin production is specific to pancreatic beta cells, while hormone release pertains to various endocrine glands. Blood filtering is primarily the function of the kidneys, not skin glands. Thus, the primary function of sebaceous glands is accurately reflected in the production of oil for skin protection.