A&P Chapter 18 - Endocrine

  1. endocrine system
    • releases hormones (chemical messengers) that trigger cells to perform certain functions
    • works together with nervous system to control function of all body systems
    • hormones effect activity of cells somewhere else in the body
    • responses are slower than nervous system responses
    • effects are broader than nervous system effects
    • nervous system starts/stops release of hormones
    • hormones start/stop AP conduction
  2. target cell
    any cell affected by a hormone
  3. exocrine gland
    • produces a product (no hormones) and releases into duct
    • into body cavities, organs, surfaces
    • ex: sweat glands, oil glands, mucus glands
  4. endocrine gland
    produces hormone and secretes into blood or interstitial fluid
  5. hormone receptors
    • proteins on the surface of target cells that physically bind to hormones
    • only target cells for a given hormone have the appropriate receptors
    • most target cells have 2,000 - 100,000 receptors for a particular hormone
  6. down regulation
    • number of receptors for a specific hormone decreases when excess hormone is present in the blood
    • target cell is less responsive to the hormone
  7. up regulation
    • number of receptors for a specific hormone increases when not enough hormone is present in the blood
    • target cell is more responsive to the hormone
  8. circulating hormones
    enter blood, move through body, and act on a target cell far away
  9. local hormones
    act on neighboring cell - do not enter blood
  10. autocrine hormone
    acts on cell that produced hormone
  11. paracrine hormone
    acts on neighboring cell
  12. water soluble hormones
    • biogenic amines
    • proteins and peptides
    • eicosanoids
  13. lipid soluble hormones
    • steroids
    • thyroids
    • nitrous oxide
  14. hormone action
    • hormones bind to protein receptors at target cell
    • if water soluble - receptor is on surface of target cell - need second messenger
    • if lipid soluble - receptor is on inner surface of cell membrane - diffuse easily
  15. second messenger
    • water soluble protein (1st messenger) absorbed by G-protein on the surface of target cell
    • G-protein activates Adenylate Cyclase enzyme -> activates ATP -> activates cAMP (2nd messengers) -> activates Protein Kinases -> determines how cell responds to hormone
    • Phosphodiesterase deactivates protein K and cAMP to stop the process

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  16. hormone secretion
    • most are secreted in short bursts
    • when stimulated, secretion is more frequent
    • controlled by nervous system, chemical levels, and other hormones
Card Set
A&P Chapter 18 - Endocrine
A&P Chapter 18 - Endocrine