A&P II Exam 1

  1. What is humoral stimuli?
    When endocrine glands secrete their hormones in direct response  to changing blood levels of certain critical ions.
  2. What is the definition of a hormone?
    Hormones are chemical messengers secreted by cells into the extracellular fluids.  These messengers travel through the blood and regulate the metabolic function of other cells in the body.
  3. What are the body systems that work most closely with the endocrine system?
    Circulatory and nervous system.
  4. What is an example of neural stimuli?
    The nervous system stimulates the adrenal medulla to release norepinephrine and epinephrine.
  5. What is an example of humoral stimuli?
    PTH is secreted when calcium levels drop in the blood.
  6. What is an example of a hormonal stimuli?
    Releasing and inhibiting hormones produced by the hypothalamus regulate the secretion of most anterior pituitary hormones and in turn most anterior pituitary hormones stimulate other endocrine organs to release their hormones.
  7. What is hormonal stimuli?
    When endocrine glands release their hormones in response to other hormones.
  8. What is neural stimuli?
    When nerve fibers stimulate hormone release.
  9. What is the 1st and 2nd messenger system?
    • 1.Hormone binds receptor.  The hormone acting as the first messenger binds to its receptor in the plasma membrane. 
    • 2. Receptor activates G protein.  When it's GDP it's off.  When it's GTP it's on.
    • 3.G protein activates adenylate cyclase.
    • 4.Adenylate cyclase converts ATP to cyclic AMP.  This generates the second messesnger cAMP from ATP.
    • 5.Then cyclic AMP activates protein kinases.
  10. What are protein kinases?
    They are enzymes that phosphorylate (add a phosphate group group) various proteins, many of which are other enzymes.  Because phosphorylation activates some of these proteins and inhibits others, it may affect a variety of processes in the same target cell at the same time.
  11. what type of molecules use the 2nd messenger system?  Why don't they enter the cell.
    Proteins utilize the system because they are too big to enter the cell.
  12. where does the energy come from to drive the reactions in this system?
    It comes from GTP and ATP.
  13. What is amplification?
    Amplification is when each activated adenylate cyclase generates large numbers of cAMP molecules, and a single kinase enzyme can catalyze hundreds of reactions.  As the reaction cascades through one enzyme intermediate after another, the number of product molecules increase dramatically at each step.  It can generate millions of final product.
  14. What are the functions of cyclic AMP and protein kinases?
    Cyclic AMP activates protein kinase, protein kinase carries out the function of the hormone.
  15. What are examples of hormones that use the 2nd messenger system?
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A&P II Exam 1
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