The gland that releases hormones into the blood are part of the

Step 1: Analyze the question The question asks which body system includes glands that release hormones directly into the blood.

Step 2: Explain the concept There are two main types of glands:

• Exocrine glands release their secretions through ducts to a specific site (e.g., salivary glands, sweat glands, and the pancreas's digestive enzymes).
• Endocrine glands are ductless. They release hormones directly into the bloodstream, which carries them to target organs.

Examples of endocrine glands include the pituitary, thyroid, adrenal glands, ovaries, testes, and the islets of Langerhans in the pancreas (which release insulin and glucagon). Together, these form the endocrine system, the body's chemical coordination system.

Step 3: Evaluate the options

• A. Digestive system: Its glands (salivary glands, gastric glands) release enzymes through ducts into the alimentary canal, not hormones into the blood.
• B. Endocrine system: Correct. Its glands are ductless and secrete hormones directly into the blood.
• C. Circulatory system: The blood transports hormones, but the circulatory system does not contain the glands that make them.
• D. Respiratory system: It deals with gas exchange, not hormone secretion.

Step 4: Answer The correct option is B. endocrine system.

Exam tip: Remember "Endo = inside." Endocrine glands secrete into the blood, while exo (outside) glands secrete through ducts to the outside or into a cavity. If a JAMB question mentions "ductless glands" or "hormones into the blood," think endocrine right away.