Final answer:
Sebaceous glands are holocrine glands that secrete sebum to lubricate the skin and hair. Their function includes the self-destruction of gland cells, which are subsequently replaced, and their activity is influenced by hormonal changes, particularly during puberty.
Step-by-step explanation:
Sebaceous glands are a type of holocrine gland found throughout the body, primarily associated with hair follicles. These glands are responsible for secreting sebum, an oily substance that helps to lubricate and protect the skin and hair. The process of sebum secretion is unique because it involves the rupture and self-destruction of gland cells; after they release their contents, they are replaced by new glandular cells that form from the surrounding tissue. This secretion method ensures that the skin remains hydrated and defended against bacterial growth and water loss, especially in low-humidity environments.
During puberty, the activity of sebaceous glands increases due to hormonal stimulation, which sometimes leads to an increase in pimples among teenagers. However, these glands are relatively inactive during childhood. Sebaceous glands are crucial for maintaining the health of the skin, providing waterproofing, and preventing the skin from drying out. When these glands become plugged or infected, it can lead to the development of acne.