bone hormones

Question 1

PTH

Answer 1

Main stimulus: Low calcium in plasma, high phosphate, Low Vit D
Binding site: kidneys, bone, GIT
Actions: Increase Ca reabsorption, decrease PO4 absorption, increase D3 production, increase reabsorption of bone, GIT increase of Ca (by increased D3)
Feedback: High Ca and high 1,25 OH D3 (active D3)

Question 2

Calcitonin

Answer 2

Main stimulus: High Calcium
Binding site: GIT, kidney, bone
Actions: Main site is GIT to stop Ca absorption, Kidney reduces everything Ca, PO4 and D3, Bone increases deposition
Feedback: Low Ca

Question 3

Vitamin D

Answer 3

Main stimulus: High PTH or low Ca
Binding site: nuclear receptors in GIT
Actions: In GIT increase Ca channel transcription, kidneys to increase Ca and PO4 reabsorption, bone it increases reabsorption
Feedback: High Ca or low PTH

Question 4

FGF-23

Answer 4

Produced in: Liver
Main stimulus: high Vit D or high PO4
Binding site:
Actions: Decreases PO4 reabsorption in kidney, inhibits Vit D production, Inhibits PTH
Feedback: