What is the primary role of exocrine glands?

Exocrine glands are primarily responsible for secreting substances through ducts. This function distinguishes them from endocrine glands, which release hormones directly into the bloodstream. The substances produced by exocrine glands can include enzymes, sweat, saliva, and mucus, which are essential for various bodily functions such as digestion, thermoregulation, and lubrication.

When considering the other roles listed, producing hormones pertains specifically to endocrine glands rather than exocrine. Regulating metabolism is also primarily associated with endocrine glands, such as the thyroid gland, which plays a crucial role in metabolic processes. Storing nutrients is not a function attributed to glands but rather to organs such as the liver, which plays a key role in nutrient storage and metabolism. Therefore, the correct response highlights the unique ductal secretion function of exocrine glands.