Calcium Homeostasis - Hockerman

Question 1

Osteoblasts

Answer 1

bone forming

bring in Ca and PO4 from plasma into the bone

Question 2

Osteoclasts

Answer 2

bone reabsorption

release calcium and PO4 from the bone into the plasma

Question 3

Osteocytes

Answer 3

regulate the osteoblasts and -clasts

stimulated by mechanical force (actin and connexin)

Question 4

PTH

Answer 4

increase serum calcium by upregulating osteoclast activity
increase PO4 loss in urine
increase D3 production
*release trigged by low serum calcium levels

Question 5

Vit D

Answer 5

cholecaciferol
increases calcium and PO4 reabsorption 
inhibits PTH
in absence of PTH converts to secalciferol 
if PTH is presents, become calcitriol

Question 6

Calcitriol

Answer 6

most active form of Vit. D

synthesized when PTH is present and calcium and Phos are low in serum

Question 7

FGF23

Answer 7

Fibroblast Growth Factor
Secrected by osteocyctes and osteoblasts when serum phosphate is elevated
inhibits PTH and 1,2OHD
inhibits bone mineralization

Question 8

calcitonin

Answer 8

secreted by thyroid when serum calcium is high
inhibits bone reabsorption via osteoclasts
Increases loss of calcium and phosphate in the urine

Question 9

Pagets

Answer 9

uncontrolled osteoclastic reabsorption

bone pain, deformities, loss of hearing

Question 10

postmenopausal osteoporosis

Answer 10

decreased estrogen causes decreased bone mass

higher amount of osteoclasts

Question 11

Aging osteoporosis

Answer 11

decreased number of osteoblasts

Question 12

biphosphonates

Answer 12

treatment for osteoporosis
inhibit bone reabsorption
accumulate in the bone matrix
reduces osteoclasts activity by inhibiting FPS

Question 13

Estrogens/SERMS for osteoporosis

Answer 13

prevent the postmenopausal bone resorption
increase osteoblasts while decreasing osteoclast activity
estrace, premarin, raloxifene

Question 14

Raloxifene

Answer 14

SERM used to prevent osteoporosis
less side effects and risks of cancers than estrogens
higher risks of clots

Question 15

Calcitonin

Answer 15

decreased osteoclast activity

blocks reabsorption of PO4 and calcium from the bone

Question 16

teriparatide

Answer 16

based on PTH
stimulates osteoblast activity with intermittent pattern of administration
Continuous administration leads to an increase of bone resorption
use short term

Question 17

denosumab

Answer 17

monoclonal ab that is against RANKL
binding prevents osteoclast differentiation
need to supplement calcium and vitamin D daily

Question 18

Cinacalcet

Answer 18

used in CKD with dialysis
binds to calcium receptors to inhibit PTH release
decreases serum calcium levels
Makes calcium receptors more responsive (PAM)
similar to zemplar and hectorol

Question 19

Fosrenol

Answer 19

Binder that forms insoluble salts in the GI tract

decreases calcium and phosphorus levels

Question 20

Renagel

Answer 20

Binds to phosphate in GI tract

selectively decreases the phosphate levels