The endocrine system (hormonal system) is the collection of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things.
The endocrine system chemically controls the various functions of cells, tissues, and organs through the secretion of hormones. The endocrine system includes the adrenal glands, parathyroid gland, pituitary gland, and thyroid gland, as well as the ovaries, pancreas, and testes.