Anatomy

Parathyroid Anatomy

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Parathyroid Anatomy, Parathyroid Gland, Parathyroid

  • Anatomy
  1. Images
    1. entParathyroidGrayBB1177.gifLewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
  2. Four Parathyroid Glands in neck, adjacent to the Thyroid Gland
    1. One gland positioned behind each of Thyroid poles
    2. Parathyroid Glands may be positioned in the superior mediastinum in some cases
  • Physiology
  1. Images
    1. CalciumHomeostasis.png
  2. Parathyroid Gland regulates extracellular Calcium
    1. Parathyroid synthesizes Parathyroid Hormone (PTH)
  3. Parathyroid increases PTH release when Calcium falls
    1. See Parathyroid Hormone for PTH physiology
    2. Parathyroid cells have a Calcium sensing receptor (CASR), triggered in Low Serum Calcium states
    3. PTH rises when Calcium falls, and increases Serum Calcium
      1. Stimulates Osteoclast activity to resorb bone
      2. Decreases renal Calcium excretion
      3. Stimulates intestinal Calcium absorption
    4. PTH falls when Calcium rises, and decreases Serum Calcium
      1. Negative feedback loop
  • Pathophysiology