bone mineral homeostasis

Question 1

what are the control sites for plasma Calcium and PO4

Answer 1

gut, blood, bone. kidney

Question 2

which bone cell is responsible for deposition of bone

Answer 2

osteoblasts

Question 3

which bone cell is responsible for resorption of bone

Answer 3

osteoclasts

Question 4

how are osteoclasts activated? draw a flowchart.

Answer 4

hormones activate osteoblasts
osteoblasts secrete RANK ligand
RANK ligand activates osteoclasts

Question 5

Parathyroid hormone promotes or inhibits

______ bone resorption
_______ Ca absorption in the kidney
_______ PO4 excretion

Answer 5

promotes
promotes
promotes

Question 6

What is the net affect of PTH on Calcium and PO4`

Answer 6

increase calcium

decrease (sort of) PO4

Question 7

what is PTH 1-34

Answer 7

synthetic parathyroid hormone

Question 8

what is teriperatide ?

what is it used for?

Answer 8

PTH 1-34, synthetic hormone

osteoperosis

Question 9

how does PTH affect the kidney ASIDE from affecting the Ca and PO4 concentrations?

Answer 9

stimulation of vitamin D processing

Question 10

T or F
PTH directly promotes bone resorption.
explain

Answer 10

FALSE
not directly, INDIRECTLY.
PTH –> osteoblast —–> RANKL ——> osteoctye ——> resorption

Question 11

where is vitamin D metabolized

Answer 11

liver then kidney

Question 12

what is vitamin D metabolized into? (2)

Answer 12

calcitriol (active form)

secalciferol

Question 13

Vitamin D3: (fill in the blanks)

________ Ca excretion
_______ PO4 excretion
________ Ca concentration through bone resorption
_________ PO4 concentration through bone resorption

Answer 13

decrease
decrease
increase
increase

Question 14

how does vitamin D affect Ca and PO4 in the gut?

Answer 14

promotes uptake

Question 15

what are Ca levels sense by?

Answer 15

Ca receptors in the parathyroid

Question 16

PTH exerts effects on PTH receptors in the _______ and _______

Answer 16

kidney and osteoblasts

Question 17

PTH stimulation of vitamin D metabolism leads to vitamin D effects in _____, _____ and _____

Answer 17

gut, kidney and bone

Question 18

what is the active form of Vitamin D

Answer 18

1,25 form

Question 19

what are the effects of FGF23?

Answer 19

inhibits phopshate uptake
inhibits D3 metabolism
inhibits PTH production

Question 20

what are the effects of calcitonin?

Answer 20

INHIBITS bone resoprtion

inhibits calcium and phosphate reabsorption in kidney

Question 21

where was calcitonin discovered, and by whom?

Answer 21

UBC, D.H Copp

Question 22

what effects do glucocorticoids have on bones? why?

Answer 22

osteoporosis

because it blocks calcium uptake in gut and promotes excretion in the kidney

Question 23

how do estrogens affect bones?

Answer 23

PREVENT bone loss in postmenopausal women

direct effects in bone, prevents PTH stimulated resorption

Question 24

what is hypocalcemia?

Answer 24

too little calcium

Question 25

how can hypocalcemia be treated?

Answer 25

calcium (oral, iv or im) | or an active vitamin D3 metabolite

Question 26

what are the negative effects of hypocalcemia?

Answer 26

hyperexcitability in cells | seizures, muscle tetany, spasms

Question 27

what is the long-term danger of hypocalcemia:? | what does it cause?

Answer 27

HYPERPARATHYROIDISM | weakening of bones

Question 28

what is the long term underlying defect causing hypocalcemia?

Answer 28

hypoparathyroidism vitamin D deficiency

Question 29

how can hypoparathyroidism be treated?

Answer 29

vitamin D OR calcium supplements

Question 30

how can vitamin D deficiency be treated

Answer 30

ingestion of active vitamin D3 metabolites (like calcitrol) | sunshine

Question 31

how does hypercalcemia affect cellular excitability

Answer 31

loss of cellular excitability

Question 32

lethargy is caused by _____ | hyper or hypocalcemia

Answer 32

hypercalcemia

Question 33

what is the long-term cause of hypercalcemia usually?

Answer 33

primary hyperparathyroidism

Question 34

what are calciimimetics? what do they treat?

Answer 34

synthetic calcium, mimic calcium affect on receptors to increase excitability hypercalcemia

Question 35

name 3 modes of therapy for hypercalcemia?

Answer 35

1. resection of PT gland 2. protect the bone 3. calcimimetics

Question 36

which demographic is most affected by osteoperosis?

Answer 36

aging females

Question 37

what is teriparatide? | what does it treat?

Answer 37

recombinant fully active PTH fragment | osteoporosis

Question 38

why is teriparatide strange? how does it work despite this feature?

Answer 38

it is meant to fix osteoporosis, but it is a PTH fragment. must be timed correctly to tip balance to osteoblast activity rather than RANKL activation of osteoclasts

Question 39

what are biphosphates used for clinically? how do they work? what is the side affect that they are speculated to have?

Answer 39

osteoporosis inhibition of osteoclast resorption of bone inhibit glucocorticoid effects

Question 40

what is alendronate?

Answer 40

biphosphate

Question 41

what structure do all biphosphates have?

Answer 41

2 phosphonate groups

Question 42

what is osteoprotegerin ? how does it work?

Answer 42

binds to RANKL to inhibit RANK

Question 43

PTH is a _____ | peptide or steroid hormone

Answer 43

peptide