Parathyroid Gland S2M1

  1. What does the parathyroid gland arise from
    From endoderm of the 4th Pharyngeal arch for the superior glands, 3rd for the inferior
  2. What are the two cell types that the parathyroid is made up of
    • Principle chief cells (polygonal)
    • Oxyphil cells (larger cells with unknown function)
  3. How do chief cells respond to low Ca++
    Secrete PTH (Parathyroid hormone)
  4. What are the three main targets of PTH
    • Osteoblasts
    • Kidneys
    • Intestines
  5. What is the effect of PTH on Osteoblasts
    Osteoblasts release Osteoclast releasing factors triggering osteoclasts to resorb bone increasing Ca++ into the blood
  6. What is the effect of PTH on Kidneys
    • Increases Ca++ absorption
    • Decrease PO4 absorption
    • Cause formation of Vit D (calcitriol)
  7. What is the effect of PTH on the intestines
    Promotes intestinal absorption of Ca++ via Vit D
  8. High Ca+ has what effect on calcitonin
  9. Where does the majority of body calcium end up
  10. In what ways can calcium be found in the blood stream
    • Bound to plasma proteins
    • Bound to extracellular anions (citrate, phophate, ect.)
    • Free calcium - ionized and difussible
  11. What is the functional calcium in the blood stream that is used for diagnostic testing
    Ionized (free calcium) which makes up 50% of the plasma calcium
  12. What is the pathway for inhibition of PTH release from Chief cells
    • High Ca+ in the blood binds Ca+ receptors
    • G-protein activated
    • IP3 releases Ca+ from the ER
    • Ca+ inhibits the release of PTH from intracellular vesicles
  13. How are Ca and Phosphate related
    They have an inverse relationship
  14. How are Calcitonin and PTH related
    They are inversly related with PTH being high in Hypocalcemia and Calcitonin absent, the opposite is true in Hypercalcemia
  15. 25-hydroxy cholecalciferol
    Modified version of Vit D that is converted to 1,25 Vit D (active form of Vit D) in the kidney upon binding of PTH
  16. D3
    Active form of Vit D
  17. What happens to D3 after being made in the kidney
    It goes to the intestines to increase Ca+ absorption
  18. What inhibits the formation of PTH in the Parathyroids
    • High plasma Ca+
    • Calcitriol (Vit D3)
  19. What are the different names for acitvated Vit D
    • D3
    • Calcitriol
    • 1,25-dihydroxy cholecalciferol
  20. Calcitonin is made by
    Parafollicular cells of the Thyroid gland
  21. How does Calcitonin release relate to Ca+ release
    Calcitonin release is directly proportional to plasma Ca+ (Ca+high=Calcitonin release)
  22. What is the function of Calcitonin
    • Inhibits osteoclast activity
    • Inhibits osteoclast formation
    • Minor role inhibiting absorption of Ca+ and Phosphorus in the kindeys
    • Overall reduces plasma calcium
  23. What is the main transporter for Vit D
    Vitamin D binding protein
  24. What triggers the breakdown of Vit D3
    • PO4
    • High levels of Vit D3
    • (PTH triggers its synthesis)
  25. Low PO4 in ECF triggers what actions
    • - Increase in Ca+ > Low PTH > Increase PO4 reabsorption in Kidney
    • - Increase in Vit D3 > Increase in PO4 uptake in GI tract
    • (Overall increase in PO4 in the ECF)
  26. What effect does Vit D3 (Calcitriol) have on the bones
    It triggers bone resorption increasing Ca+ in the plasma
  27. What effects do Androgens and Estrogens have on Bones
    They cause bone resorption and Osteoporosis
  28. What are the effects of Thyroid hormones, Prolactin, and Cortisol on Ca+
    • Thyroid hormones cause bone resorption
    • Prolactin causes reabsorption of Ca+ in Kidneys
    • Cortisol causes bone resorption and bone synthesis
  29. Teriparatide & Cinacalcet are what type of drugs
    Parathyroid related drugs
  30. What are the two different Vitamin D supplements
    • Cholecalciferol D3
    • Ergocalciferol D2 (Plant form)
  31. How can obesity effect Vit D
    Vit D can get sequestered in fat, trapped from the bodies ability to utilize it
  32. What is the primary therapeutic use of Calcitriol
    • Used during renal failure when the body is unable to produce it
    • It is also used to treat hypoparathyroidism
  33. Cinacalcet
    • This drug sensitizes the Ca+ receptors response decreasing the release on PTH
    • Cin-Ca-lcet
    • "Cinsitizes Ca receptors"
  34. For what conditions is Cinacalcet used to treat
    • Secondary Hyperparathyroidism (in renal disease)
    • Primary Hyperparathyroidism
    • Sometimes parathyroid carcinoma
  35. What are the adverse affects of Cinacalcet
    • Hypocalcemia
    • Possible cardiac effects
  36. What are the Calcium regulating drugs used to suppress high bone turnover
    • Teriparatide
    • Calcitonin
  37. Teriparatide is used to treat
    Osteoporosis by blocking the action of bone resorption
Card Set
Parathyroid Gland S2M1