What constitutes the endocrine system?

The endocrine system is primarily composed of glands and organs that secrete hormones directly into the bloodstream, regulating various physiological processes throughout the body. These hormones act as chemical messengers, influencing growth, metabolism, reproduction, and mood, among other functions.

While nerves and networks of blood vessels play essential roles in other physiological systems—such as the nervous system and circulatory system, respectively—they are not the main components of the endocrine system. The focus of the endocrine system is specifically on hormone-secreting glands, such as the pituitary gland, thyroid gland, and adrenal glands. Therefore, recognizing that the endocrine system is made up of organs that secrete hormones is key to understanding its structure and function.

The answer correctly identifies both the presence of hormone-secreting organs and the nature of the endocrine system, highlighting its integration with the broader physiological networks in the body.