Glands that secrete chemical substances into ducts that lead to the outside of the skin are called

• A. Endocrine glands
• B. Sweat glands
• C. Sebaceous glands
• D. Exocrine glands

Answer: (D)

Glands that release their products into ducts that carry them to the external surface are exocrine glands. The key idea is that exocrine secretions travel through ducts to reach outside the body or a body cavity, such as the skin surface with sweat or sebum. Endocrine glands, in contrast, release hormones directly into the bloodstream, without ducts. Sweat glands are classic exocrine glands, and sebaceous glands also secrete through ducts to reach the skin surface or hair follicles. So the general term for glands with ducts leading to the outside of the skin is exocrine glands.