Calcium and Bone

Question 1

how does vit D affect calcium

Answer 1

stimulates calcium absorption, increases plasma conc

Question 2

how does vit D affect phosphate

Answer 2

stimulates phosphate absorption (but less than Ca++) increases plasma conc

Question 3

how does PTH affect plasma calcium

Answer 3

increases

Question 4

how does PTH affect plasma phosphate

Answer 4

decreases

Question 5

why does PTH decrease phosphate

Answer 5

to prevent Ca++ and phosphate binding and forming crystals

Question 6

how does calcitonin (CT) affect plasma calcium

Answer 6

decrease

Question 7

how does CT affect plasma phosphate

Answer 7

decrease

Question 8

how does PTH affect kidney

Answer 8

controls amount of Ca++ reaborbed in distal portions of nephrone
inhibits phosphate reabsorption in kidney

Question 9

How does PTH affect bone

Answer 9

increases bone resorption and delivery of calcium to plasma

inhibits collagen synthesis by osteoblasts

Question 10

how does PTH affect vit D

Answer 10

it increases vit D by increasing activity of 1alpha hydroxylase.

Question 11

How does Vit D affect PTH

Answer 11

inhibits

Question 12

what are the plasma forms of calcium

Answer 12

free or ionized
protein bound
bound to small diffusible anions

Question 13

where is more than half of the total caclium found

Answer 13

free or ionized

Question 14

symptoms of hypocalcemia

Answer 14

easier to have APs, so everything is more excitable

Question 15

what signs clue you into hypocalcemia that causes latent tetany

Answer 15

trousseau or chyvostek

Question 16

symptoms of hypercalcemia

Answer 16

less likely to have an AP. also polyuria and kidney stones

Question 17

osteoblasts

Answer 17

deposit bone

Question 18

osteoclasts

Answer 18

resorption of bone

Question 19

osteoprotegerin ligand (OPGL) is also called

Answer 19

RANK ligand

Question 20

function of OPGL

Answer 20

activates receptors on preosteoclast cells, causes them to differetiate into multinucleated osteoclasts

Question 21

osteoprotegerin (OPG) function

Answer 21

acts as a decoy receptor of OPGL, prevents it from biding to its receptor on preosteroclast cells

Question 22

how does PTH affect bone resorption

Answer 22

stimulates bone resoprtion by binding to receptors on osteoblasts and causing them to release OPGL

Question 23

where is vitD3 converted to active form

Answer 23

kidney

Question 24

what is the active form of vitD called

Answer 24

1,25 dihydrorycholecalciferol

Question 25

osteomalcia

Answer 25

can be due to failure of damaged kidney to produce the active form of vit D

Question 26

signs of primary hyperparathyroidism

Answer 26

hypercalcemia, hypophosphatemia

Question 27

symptoms of primary hyperparathyroidism

Answer 27

formation of calcium containing kidney stone
weak bones
constipation, excessive urination

Question 28

when does secondary hyperparathyroidism happen

Answer 28

pt with disease that cause chronically low plasma calcium

Question 29

symptoms of hypoparathyroidism

Answer 29

low calcium causes neuromuscular hyperexitability, hypocalcemic tetany

Question 30

pseudohypoparathyroidism

Answer 30

have signs and symptoms of hhypoparathyroidism but their circulating level of PTH is normal or elevated