Which organ system controls internal communication and regulation via hormones?

• A. Nervous system
• B. Endocrine system
• C. Digestive system
• D. Circulatory system

Answer: (B)

The main idea being tested is how the body communicates and maintains regulation through chemical messengers released into the bloodstream. The endocrine system handles this chemical signaling, releasing hormones from glands such as the pituitary, thyroid, adrenal, and pancreas to target organs and tissues. These hormones coordinate processes like growth, metabolism, and stress responses, keeping the body's internal environment stable over longer timescales than rapid neural signals. While the nervous system also regulates the body, it does so mainly through fast electrical communication, not through hormones. The digestive system focuses on breaking down and absorbing nutrients, and the circulatory system transports blood (including hormones) but does not primarily regulate bodily functions via hormonal signaling. Therefore, the endocrine system is the component responsible for internal communication and regulation through hormones.