The endocrine system is made up of glands (like the pituitary, adrenal, thyroid, and parathyroid glands, the pancreas, and the ovaries or testicles) throughout the body. Endocrine glands secrete hormones, or body chemicals, into the bloodstream.

The endocrine system affects many different body functions, including growth and the production of energy (metabolism). Disorders of this system can result in problems such as diabetes, hyperthyroidism and hypothyroidism, or Addison's disease.