Hormonal regulation Flashcards
State activation vit D?
1) 7-dehydrocholesterol exposed UV light (skin)
2) Converted to cholecalciferol
3) In liver 25 hydroxylase catalyses conversion cholecalciferol to 25-hydroxyvitamin D3 (calcediol)
4) In kidney 1 alpha hydroxylase converts 25-hydroxyvitamin D3 to 1-25 dihydroxyvitamin D3 (calcitriol)
State 3 effects of 1-25 dihydroxyvitamin D3 (calcitriol)?
1) Intestine- increase calcium uptake
2) Bone- increase bone resorption- increase serum calcium and phosphate
3) Kidney- dct- increase calcium reabsorption
4) Suppress PTH
State 3 functions of PTH?
1) Kidney-DCT/PCT- Increase phosphate excretion
2) Kidney- thick asc LOH- Increase calcium resorption
3) Bone- increase resorption- increase serum calcium and phosphate
What secretes PTH?
Parathyroid chief cells
What secretes calcitonin?
When is it secreted?
C cells of Thyroid gland
Hypercalcemia- high lvls serum calcium
State 3 functions calcitonin?
1) Inhibit PTH
2) Intestine- decrease calcium uptake
3) Inhibit bone resorption
4)Kidney- inhibit calcium resorption
When is PTH released?
Hypocalcaemia
Low lvls serum calcium
Where is 7-dehydrocholseterol converted to cholcalciferol?
Skin
Where is cholecalciferol converted to calcidiol?
Liver
Where is calcidiol converted to calcitriol?
Kidney
Draw activation vit D3
State catalysts involved vitD3?
1) UV light (skin)
2) 25-hydroxylase (liver)
3) 1a-hydroxylase (kidney)
List 3 places where PTH acts directly on?
Kidney
Bone
SI
What occurs if hypocalcemia?
1) Parathyroid gland- chief cells detect low Ca2+
2) Increase PTH secretion
3) Kidney- increase calcitriol (vit D3)
- decrease calcium excretion
4) Bone- release calcium and phosphorous
5) SI- increase absorption calcium
6) DECREASE serum phosphate
7) INCREASE serum calcium
How is serum phosphate effected by increased PTH release?
Decreased
