Regulation of Calcium + Phosphate

Question 1

Where is 99% of calcium found?

Answer 1

Stored in bones + teeth

Question 2

What form of calcium = active?

Answer 2

The free (ultrafilterable), ionized ca++ = active –>can cross plasma membrane

50%

Question 3

If a person has hyperreflexia, spontaneous twitching, muscel cramps, and tingling and numbness what do they have?

Answer 3

Hypocalcemia (low blood calcium)

Question 4

What 2 signs are seen in hypocalcemia?

Answer 4

Chvostek sign (facial muscle twitch)

Trousseau sign (carpopedal spasm when blood pressure cuff is inflated)

Question 5

What disease shows symptoms of constipation, lack of appetite, luscle weakness, lethargy, coma?

Answer 5

hypercalcemia (increased serum calcium)

Question 6

Does hyper or hypocalcemia increase membrane excitability (spontaneous APs) via lowering the acivation threshold?

Answer 6

Hypercalcemia

Question 7

If you are acidodic, will you have more or less bound calcium?

Answer 7

less bound and more free cause albumin is neg.

Question 8

If you are alkalotic, will you have more or less calcium bound to albumin?

Answer 8

more

Question 9

What percentage is phosphate (Pi) is stored in bone?

Answer 9

85%

Question 10

Which cells secrete PTH?

Answer 10

The chief cells of the parathyroid gland

Question 11

What is the stimulus for PTH secretion?

Answer 11

decreased plasma calcium

Question 12

Increased synthesis + storage of PTH would be seen in?

Answer 12

Chronic hypocalcemia

Question 13

Decreased synthesis and storage of PTH would be seen in?

Answer 13

Chronic hypercalcemia

Question 14

In alcoholics, they tend to have chronic Magnesium depletion. What does this do to PTH?

Answer 14

Hypomagnesemia inhibits PTH synthesis

Question 15

When PTH and Vit. D bind to their G protein linked receptor, this does what?

Answer 15

Increases cAMP

Question 16

What is the active form of Vit. D?

Answer 16

1,25-dihydroxycholecalciferol

Question 17

What does bone resorption mean?

Answer 17

It takes calcium from the bone and puts it into circulation to raise blood calcium.

Question 18

What does PTH do to calcium and phosphate levels?

Answer 18

It wants to increase blood calcium and decrease phosphate

Question 19

What is interesting about Vitamin D?

Answer 19

It increases BOTH calcium and Pi

Question 20

What is another name for Vitamin D?

Answer 20

cholecalciferol

Question 21

What hormone works to promote mineralization of new bone?

Answer 21

Vitamin D

Question 22

What hormone with the stimulus of decreased calcium and phosphate and increased PTH, converts inactive vitamin D to its active form?

Answer 22

1 alpha-hydroxylase

(AKA CYP1alpha)

Question 23

What part of bone are PTH receptors located on?

Answer 23

OsteoBLASTS

Question 24

What steroid hormone acts synergistically with PTH to help with bone formation and resorption?

What are the short term and long term effects?

Answer 24

Vitamin D

short term actions: bone formation (direct effect on osteoblasts)

long term actions: bone resorption (indirect effect on osteoclasts)

Question 25

What is the primary mediator of osteoclast formation?

Answer 25

RANKL

Question 26

What are the specific action of PTH and Vit D on bone formation and resorption?

Answer 26

PTH: Increases RANKL and decreases OPG Vit. D: Increases RANKL

Question 27

What inhibits RANKL?

Answer 27

OPG (osteoprogeritin)

Question 28

What is RANK?

Answer 28

cell surface protein receptor on osteoclasts

Question 29

What are osteoblasts?

Answer 29

form new bone

Question 30

What are osteoclasts?

Answer 30

Resorb old bone

Question 31

In the kidney, what causes posphaturia (increased excretion of phosphate)?

Answer 31

Inhibition of NPT by PTH

Question 32

Describe how PTH affects calcium and phosphate homeostasis?

Answer 32

Question 33

Describe how Vitamin D affects calcium and phosphate homeostasis:

Answer 33

Question 34

What is secreted when there is high blood calcium?

Answer 34

Calcitonin

Question 35

What inhibits bone resorption?

Answer 35

Calcitonin

Question 36

Primary hyperparathyroidism:

Answer 36

stones, bones, and groans

Question 37

Secondary Hyperparathyroidism: - Renal Failure - Vitamin D Deficiency

Answer 37

Question 38

Hypoparathyroidism

Answer 38

Question 39

Albright Hereditary Osteodystrophy: Pseudohypoparathyroidism Type 1a

Answer 39

Gs defective (no cAMP) Short neck, short stature

Question 40

Humoral Hypercalcemia of malignancy

Answer 40

Increased PTHrP levels

Question 41

Familial Hypocalciuric Hypercalcemia

Answer 41

Overproducing calcium, but can't detect it cause calsium sensor (CaSR) is mutated

Question 42

Vitamin D deficiency

Answer 42

Rickets (kids) type 1: Decreases 1 alpha-hydroxylase type 2: decreased vitamin D receptor Osteomalacia (adults)