The Endocrine 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. This collection of glands is made up of the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries (in females) and testicles (in males), as well as the liver and kidneys. Each of these glands secretes one or more different hormones in the blood for different functions.