The endocrine system consists of glands that secrete hormones directly into the bloodstream to regulate distant target organs and tissues. The major glands include the pituitary gland, thyroid gland, parathyroid gland, adrenal glands, pancreas, ovaries, testes, pineal gland, and hypothalamus. Each gland secretes specific hormones that control important body functions such as growth and development, metabolism, sexual functions, reproduction, and the stress response.