HUMAN SYSTEMS QUESTION 1984           L. PETERSON/AP BIOLOGY

            Discuss the sources and actions of each of the following pairs of hormones in 
	humans and describe the feedback mechanisms that control their release.
		a.  Insulin..glucagon
		b.  Parathyroid hormone..calcitonin
		c.  Thyrotropin (TSH)..thyroxine (T4)
  
  
  STANDARDS:
     Maximum of any 6 points on each of three sections.
     Must answer all three sections of exam to score 15.
     Discretionary point on adequate discussion of feedback loop and/or homeostasis.
  
  INSULIN/GLUCAGON SECTION
  INSULIN:
   SOURCE
     2 - Beta cells of pancreas
     1 - Pancreas or Islets of Langerhans
   ACTION
     1 - Lowers blood sugar
     1 - Promotes glucose oxidation in cells
     1 - Glycogen synthesis (liver and muscle)
  RELEASE
     1 - Chemical - blood glucose level
     1 - Hormonal - secretin, gastrin, etc.
     1 - Neural - Acetylcholine (parasympathetic) stimulates
  GLUCAGON:
  SOURCE
     2 - Alpha cells of pancreas
     1 - Pancreas or Islets of Langerhans
  ACTION
     1 - Increases blood glucose
     1 - Stimulates glycogen -> glucose (liver)
     1 - Synthesis of glucose from amino acids and fatty acids
  RELEASE
     1 - Level of blood glucose, i.e. low glucose / increases glucagon
     1 - Neural - Autonomic system
  PARATHYROID HORMONE/CALCITONIN SECTION
  PARATHYROID HORMONE:
  SOURCE
     1 - Parathyroid gland on posterior surface of thyroid
  ACTION
     1 - Control of Ca (inc.) and P (dec.) level
     1 - Acts on bones, kidneys, and intestine
     1 - Increases activity of osteoclasts (Ca and P bone -> blood)
     1 - Kidney Ca reabsorbed, P excreted
  RELEASE
     1 - Blood Ca low, PTH high  (vice-versa)
  CALCITONIN:
  SOURCE
     1 - Cells in thyroid gland
  ACTION
     1 - Decreases osteoclast activity
     1 - Inhibits release of Ca and P from bone
     1 - Lowers blood Ca and P
  RELEASE
     1 - Increased blood Ca causes increase in Calcitonin
  THYROTROPIN/THYROXINE SECTION
  THYROTROPIN
  SOURCE
     1 - Anterior Pituitary
  ACTION
     1 - Stimulates thyroid hormone synthesis and secretion
     1 - Increases iodide binding, T3, T4 synthesis
     1 - T3, T4 release
  RELEASE
     1 - Thyroid Hormone level decreases, TSH increases (vice-versa)
  THYROID HORMONE
  SOURCE
     1 - Follicles of thyroid gland or thyroid gland
  ACTION
     1 - Maintains metabolic level
     1 - Increases O2 consumption
     1 - Maintains normal development and function
  RELEASE
     1 - Neural via hypothalamus (low thyroid hormone, increases TSH)
     1 - TSH feedback (thyroid and anterior pituitary