The primary role of the endocrine system is to produce and secrete hormones that regulate various physiological processes in the human body. This system plays a crucial role in controlling metabolism, growth, reproduction, and mood. Hormones released by glands such as the pituitary, thyroid, and adrenal affect numerous target organs and tissues, causing a range of effects. The endocrine system works in conjunction with the nervous system to maintain homeostasis and ensure the body responds appropriately to internal and external stimuli.