Topic Three

• what element is thyroglobulin modified with

  iodine
• follicular cells produce, store and secrete thyroid homrones
• three major types of thyroid hormones

  1. thyroxine (T4)
  2. triodothyromine (T3)
  3. reverse triodothyromine (rT3)
• when a thyroid follicle is active it has a small colloid
• when a thyroid follcile is inactive it has a large colloid
• Thyroid hormone is regualted by a negative feedback loop
• Na+/I- symporter;

  • [Na+] in cell is 2-10mM
  • [Na+] outside cell is 150mM
  • the differnece in [] allows Na+ to drag I- atoms into the cell
• Pendrin

  • Na+ independent
  • electroneutral Cl- or I- exchange with HCO3
• Outer ring deiodination produces

  T3
• Outer ring deiodination uses enzymes deiodinases I and II
• Type I deiodinase acts on;

  1. liver
  2. thyroid
  3. kidney
• Type II deiodinase acts on;

  1. brain
  2. pituitary
  3. placenta
• Inner ring deiodination produces 


  Reverse T3
• Thyroid hormone binding proteins present in the blood;

  1. Thyroid hormone binding globulin (TBG)
  2. thyroid hormone binding prealbumin (TBGA)
  3. albumin
• When T4 is bound to one of these receptors it does not actively diffuse away to respective tissues
• which domain is responsible for DNA-binding

  C
• which domain is responsible for hinge 


  D
• which domain is responsible for hormone binding

  E
• What is the parathryoid hormone repsonsible for

  Calcium homeostasis
• What do parafollicular cells do;

  • produce and secret calcitonin
  • regulate mineral homestasis
  • peptide hormone
• What do principle cells do;

  • produce and secrete PTH
  • peptide hormone
• how many glands make up the parathyroid gland

  4
• which orans do the parathroid hormone work on

  kindey and intestine
• what is the role of the kidney in homeostasis

  filters calcium
• what is the role of intestine in homeostasis

  absorbs calcium