Final answer:
The statement is False; the endocrine system includes glands that secrete hormones as their primary function, as well as other organs and tissues with secondary endocrine functions.
Step-by-step explanation:
The statement that the endocrine system is comprised only of glands whose primary function is the secretion of hormones is False. While the endocrine system does consist of major endocrine glands like the pituitary, thyroid, parathyroid, adrenal, and pineal glands, it also includes organs and tissues that perform both endocrine and non-endocrine functions. For instance, the pancreas has exocrine functions related to digestion as well as endocrine functions, secreting hormones like insulin and glucagon which regulate blood glucose levels. Other organs such as the heart, kidneys, liver, and even adipose tissue, produce hormones as well, underscoring the diverse nature of the endocrine system's components.
These organs and tissues secrete hormones into the bloodstream, acting as chemical messengers that regulate various physiological processes throughout the body. This system is intricately linked with the nervous system to maintain homeostasis and respond to environmental changes. Therefore, the endocrine system is not comprised solely of glands with the primary function of hormone secretion; it includes additional structures that perform vital secondary endocrine roles.