Endocrine system

• Hormone

  A chemical substance produced by an endocrine gland and carried by the blood
• Hormones

  • Transmit information about a change
  • Alter the activity of one or more specific target organs
  • Control functions that do not need instant responses
• Endocrine glands

  • Produce hormones in animals
  • Known collectively as the endocrine system
• Gland

  A group of cells that produces and releases one or more substances (secretion)
• Hormones

  • Insulin
  • ADH
  • Adrenaline
• Endocrine glands have a good blood supply because they need to get hormones into the bloodstream as soon as possible
• Hormones

  Only affect cells with receptors that the hormone can bind to
• Receptors

  • Found on the cell surface membrane or inside cells
  • Have to be complementary to hormones for there to be an effect
• Peptide hormones

  • Insulin
  • Glucagon
  • ADH
• Peptide hormones

  • Water soluble
  • Cannot cross the phospholipid bilayer of cell surface membranes
• Peptide hormone signaling

  1. Bind to receptors on cell surface membranes

  2. Activate second messengers

  3. Transfer the signal throughout the cytoplasm
• Steroid hormones

  • Testosterone
  • Oestrogen
  • Progesterone
• Steroid hormones

  • Lipid soluble
  • Can cross the phospholipid bilayer
• Steroid hormones bind to receptors in the cytoplasm or nucleus of their target cells