Learn all about the endocrine system with new, precise, yet easy-to-understand, definitions and explanations. The endocrine system, a group of glands, gives off specialized hormones, chemical messengers that organize and deliver messages from the brain to organs and cells. We learn about the functions of the pituitary, thyroid, parathyroid, adrenal glands and adrenaline; the function of the pancreas and insulin; how the endocrine system works; malfunctions of the hormone system like diabetes. Detailed graphics, diagrams, video, and multiple-choice reviews reinforce important concepts.