Endocrine Glands

• The endocrine system is comprised of ductless glands that release chemicals into the blood to regulate body functions
• A hormone is a chemical messenger transported via the bloodstream to act on distant target cells
• Hormones are specific and will only activate cells or tissues that possess the appropriate target receptor
• The endocrine system is slower to initiate but has a more prolonged response compared to the nervous system
• Endocrine glands secrete hormones directly into the bloodstream, unlike exocrine glands that use ducts
• Major endocrine glands include the pancreas, adrenal gland, thyroid gland, pineal gland, and the gonads (ovaries and testes)
• The hypothalamus and pituitary gland are neuroendocrine glands that link the nervous and endocrine systems
• Some organs, like adipose tissue, can also secrete hormones despite not being endocrine glands (e.g., leptin)