Final answer:
The endocrine system contains glandular structures that direct long-term changes in the activities of other organ systems by secreting hormones that circulate throughout the body. These hormones stimulate a response in cells to affect the functioning of the organ system.
Step-by-step explanation:
The endocrine system contains glandular structures that direct long-term changes in the activities of other organ systems. Endocrine glands and cells are located throughout the body and play an important role in homeostasis. These glands secrete hormones directly into the blood, which circulate throughout the body and stimulate a response in cells that have receptors to bind with them. The changes brought about by these hormones affect the functioning of the organ system to which they belong.