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ENR Biweekly 3 > Sayner- calcium and phosphate metabolism > Flashcards

Sayner- calcium and phosphate metabolism Flashcards

1
Q

Calcium intake via the intestine is dependent upon ____

A

vitamin D

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2
Q

excretion of calcium via

A

kidney

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3
Q

reservoir of calcium

A

bone

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4
Q

major calcium reservoir is found in the bone, and this accounts for about ____% of total body calcium

A

99%

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5
Q

Sx’s that occur with hypercalcemia when levels are above 11.5

A

stones, bones, abdominal groans, psychiatric overtones

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6
Q

50% of total body calcium found as what form

A

free ionized (active)

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7
Q

total plasma calcium

A

8.5-10.6 mg/dL

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8
Q

Calcium and ______ homeostasis are intimately tied together

A

phosphorus

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9
Q

Phosphate uptake in the small intestines is dependent upon ______

A

vitamin D

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10
Q

excretion via kidneys and stored in bone and soft tissue

A

phosphate

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11
Q

85% of phosphate stored in _____ as hydroxyapatite crystals

A

bone

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12
Q

90% of total body phosphate is in the form of what

A

free ionized- active

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13
Q

> 11.5 mg of calcium

A

hypercalcemia

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14
Q

< 8.5 mg/dL of calcium

A

hypocalcemia

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15
Q

_____ affects on bone:
resorption-osteoblast mediated regulation of osteoclast activity- increase in serum calcium

A

PTH (parathyroid hormone)

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16
Q

_____ affects on kidney:
increase calcium reabsorption, decrease phosphate reabsorption, increase vitamin D

A

PTH (parathyroid)

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17
Q

secreted by chief cells of the parathyroid gland

A

PTH

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18
Q

located on posterior aspect of thyroid

A

4 parathyroid glands

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19
Q

____ cells have calcium receptor that acts as sensor for free Ca2+

A

chief cells

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20
Q
A

chief cells

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21
Q

calcium sensor on Chief cells

A

PTH

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22
Q

As serum free calcium levels drop, inhibition is lost and _____secreted

A

PTH

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23
Q

Elevated Ca2+ and vitamin D inhibit _____synthesis

A

PTH

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24
Q

elevated phosphorus stimulates ____

A

PTH

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25
Q

peptide hormone—-synthesized in endoplasmic reticulum

A

PTH

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26
Q

The 84 residue ______ can be broken down in the secretory vesicle into the N- and C-terminal fragments, which are then released into the circulation.

A

PTH

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27
Q

active fragment of 84 PTH residue

A

short N-terminal

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28
Q

Active ____ is proteolytically cleaved secretory vesicles (chief cells) and liver (circulation) into 2 fragments

A

PTH

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29
Q

PTH binds ____ expressed on bone and kidney

A

PTH-R1

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30
Q

breakdown of bone tissue to release stored calcium and phosphate

A

bone resorption

31
Q

PTH effect on bone

A

resorption (release calcium into blood)

32
Q

PTH effect on kidney

A

regulates calcium reabsorption, phosphate excretion, and synthesis of vitamin D

33
Q

_____ is mineralized by hydroxyapatite crystals which are primarily calcium phosphate. In other words, ____ is a reservoir for calcium and phosphate

34
Q

_______reside on the surface of bone and secrete the unmineralized matrix (osteoid) and regulate mineralization of bone

A

osteoblasts

35
Q

more _____ than phosphate in bone reservoir

36
Q

deposit matrix and calcifies it

A

osteoblasts

37
Q

resorb/remove bone

A

osteoclasts

38
Q
A

osteoclast

39
Q

_______ are derived from hematopoetic stem cells. The common myeloid precursor differentiate into ganulocyte/monocyte precursor cells – these cells fuse to form a large multinucleated cell which is the _____ precursor. (stimulated by M-CSF, TNF, ILs)

A

osteoclast

40
Q

during maturation of osteoclasts, the _____(receptor) is expressed on osteoclast precursors

41
Q

bind PTH-R1 expressed on Osteoblasts – activates Gs signaling to increase cAMP
Increases expression of RANK-L and decrease OPG, thereby increasing osteoclastogenesis and bone resorption

42
Q

inhibits collagen synthesis by osteoblasts and promotes release of proteases (that would go ahead and degrade bone tissue)

43
Q

In a condition of low free calcium, persistent/continuous release of ____ acts on osteoblasts to promote osteoclast differentiation and activity

44
Q

Increased ______ activity releases calcium and phosphate stores from bone thereby elevating serum calcium and phosphate

A

osteoclast

45
Q

Intermittent or pulsatile ______release: anabolic effect and increases bone density
therapy now for osteoporosis

46
Q

anchors onto bony tissue; secretes protons and chloride onto bone; acid dissolves the calcium phosphate crystals

A

osteoclast

47
Q

Binding ____ to PTH-R1 increases cAMP via Gs and activates CREB which increases expression of calcium channels – transcellular transport; increase calcium reabsorption via transcellular route (at the kidneys)

48
Q

Binding of the _____ leads to internalization of phosphate transporters (and inhibition of phosphate reabsorption)

49
Q

in the PCT of kidneys, ______ stimulates vitamin D production by increasing 1⍺-hydroxylase expression which hydroxylates inactive 25-hydroxycholecalciferol to the active form of vitamin D – 1,25 hydroxycholecalciferol (1,25 (OH)2D3, calcitriol)

50
Q

fully active form of vitamin D

A

1,25 (OH)2D3 (calcitriol)

51
Q

Acts on kidney to increase expression and activity of 1-alpha-hydroxylase, which increases vitamin D

52
Q

High _____ inhibits 1alpha hydroxylase while low stimulates

53
Q

When ______ levels get high, feedback and inhibit 1-alphahydroxylase

54
Q

_______ goes to intestines where it increases calcium and phosphate reabsorption

55
Q

increases plasma calcium, increases urine phosphate

56
Q

Dietary sources of vitamin D are inactive and need to be converted to the active form, ____

A

calcitriol

57
Q

Availability of _____ is also dependent on liver and kidney function

58
Q

converts vitamin D to active form

A

1alpha-hydroxylase

59
Q

lipid soluble
Is transported through the blood bound to plasma proteins

60
Q

_______receptor is similar to steroid receptors, i.e. intracellular receptor that acts as a transcription factor to alter gene expression in target tissues. Time delay

61
Q

______ inhibits PTH at parathyroid gland

62
Q

Activation of receptor in epithelial cells (enterocytes) of the duodenum increases expression of proteins that increase calcium and phosphate absorption

63
Q

acts on osteoblasts
Increase expression of RANK-L, M-CSF to increase osteoclast differentiation (in the case of low calcium and phosphate)

64
Q

and with increased calcium and phosphate absorption from the GI tract, the net effect of _______ is to increase bone deposition

65
Q

Action of ______ is dependent on what the concentration of calcium and phosphate are in the blood

66
Q

Released by osteocytes in response to high plasma phosphate; bring phosphate levels back to homeostasis

A

FGF-23 (fibroblast growth factor 23)

67
Q

Inhibits 1⍺-hydroxylase thereby decreasing vitamin D and phosphate absorption from the gut

68
Q

Inhibits phosphate reabsorption by the kidney thereby increasing renal excretion of phosphate.
Inhibits PTH secretion

69
Q

secreted by parafollicular cells (C cells) of the thyroid gland

A

calcitonin

70
Q

released in response to high ionic calcium to bring calcium out of blood into bone

A

calcitonin

71
Q

High during gestation and lactation: to protect maternal bones

A

calcitonin

72
Q

Stimulates OPG and inhibits osteoclast differentiation

73
Q

increase osteoclast effect and decrease osteoblast effect; calcium wasting

A

glucocorticoids

74
Q

Prolonged ________therapy can lead to bone loss and osteoporosis

A

glucocorticoid

ENR Biweekly 3 (14 decks)

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