Which gland is NOT a part of the endocrine system?

• A. Exocrine
• B. Pineal
• C. Pituitary
• D. Adrenal

Answer: (A)

Glands can be classified by how they release their products. Endocrine glands secrete hormones directly into the bloodstream, so they can travel to distant targets and regulate processes throughout the body. The pineal, pituitary, and adrenal glands are classic endocrine glands because they release hormones into the blood that help control functions like sleep, growth, and stress responses.

Exocrine glands, on the other hand, release their secretions through ducts onto surfaces or into body cavities—for example, salivary glands secrete saliva into ducts in the mouth, and sweat glands release sweat onto the skin. These secretions are not hormones traveling in the bloodstream, so exocrine glands are not considered part of the endocrine system. Therefore, the gland type listed that is not part of the endocrine system is the exocrine.