Sayner- calcium and phosphate metabolism

Question 1

Calcium intake via the intestine is dependent upon ____

Answer 1

vitamin D

Question 2

excretion of calcium via

Answer 2

kidney

Question 3

reservoir of calcium

Answer 3

bone

Question 4

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

Answer 4

99%

Question 5

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

Answer 5

stones, bones, abdominal groans, psychiatric overtones

Question 6

50% of total body calcium found as what form

Answer 6

free ionized (active)

Question 7

total plasma calcium

Answer 7

8.5-10.6 mg/dL

Question 8

Calcium and ______ homeostasis are intimately tied together

Answer 8

phosphorus

Question 9

Phosphate uptake in the small intestines is dependent upon ______

Answer 9

vitamin D

Question 10

excretion via kidneys and stored in bone and soft tissue

Answer 10

phosphate

Question 11

85% of phosphate stored in _____ as hydroxyapatite crystals

Answer 11

bone

Question 12

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

Answer 12

free ionized- active

Question 13

> 11.5 mg of calcium

Answer 13

hypercalcemia

Question 14

< 8.5 mg/dL of calcium

Answer 14

hypocalcemia

Question 15

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

Answer 15

PTH (parathyroid hormone)

Question 16

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

Answer 16

PTH (parathyroid)

Question 17

secreted by chief cells of the parathyroid gland

Answer 17

PTH

Question 18

located on posterior aspect of thyroid

Answer 18

4 parathyroid glands

Question 19

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

Answer 19

chief cells

Question 20

Answer 20

chief cells

Question 21

calcium sensor on Chief cells

Answer 21

PTH

Question 22

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

Answer 22

PTH

Question 23

Elevated Ca2+ and vitamin D inhibit _____synthesis

Answer 23

PTH

Question 24

elevated phosphorus stimulates ____

Answer 24

PTH

Question 25

peptide hormone----synthesized in endoplasmic reticulum

Answer 25

PTH

Question 26

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.

Answer 26

PTH

Question 27

active fragment of 84 PTH residue

Answer 27

short N-terminal

Question 28

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

Answer 28

PTH

Question 29

PTH binds ____ expressed on bone and kidney

Answer 29

PTH-R1

Question 30

breakdown of bone tissue to release stored calcium and phosphate

Answer 30

bone resorption

Question 31

PTH effect on bone

Answer 31

resorption (release calcium into blood)

Question 32

PTH effect on kidney

Answer 32

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

Question 33

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

Answer 33

bone

Question 34

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

Answer 34

osteoblasts

Question 35

more _____ than phosphate in bone reservoir

Answer 35

calcium

Question 36

deposit matrix and calcifies it

Answer 36

osteoblasts

Question 37

resorb/remove bone

Answer 37

osteoclasts

Question 38

Answer 38

osteoclast

Question 39

_______ 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)

Answer 39

osteoclast

Question 40

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

Answer 40

RANK

Question 41

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

Answer 41

PTH

Question 42

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

Answer 42

PTH

Question 43

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

Answer 43

PTH

Question 44

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

Answer 44

osteoclast

Question 45

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

Answer 45

PTH

Question 46

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

Answer 46

osteoclast

Question 47

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)

Answer 47

PTH

Question 48

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

Answer 48

PTH-R1

Question 49

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)

Answer 49

PTH

Question 50

fully active form of vitamin D

Answer 50

1,25 (OH)2D3 (calcitriol)

Question 51

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

Answer 51

PTH

Question 52

High _____ inhibits 1alpha hydroxylase while low stimulates

Answer 52

phosphate

Question 53

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

Answer 53

vitamin D

Question 54

_______ goes to intestines where it increases calcium and phosphate reabsorption

Answer 54

vitamin D

Question 55

increases plasma calcium, increases urine phosphate

Answer 55

PTH

Question 56

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

Answer 56

calcitriol

Question 57

Availability of _____ is also dependent on liver and kidney function

Answer 57

vitamin D

Question 58

converts vitamin D to active form

Answer 58

1alpha-hydroxylase

Question 59

lipid soluble Is transported through the blood bound to plasma proteins

Answer 59

vitamin D

Question 60

_______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

Answer 60

vitamin D

Question 61

______ inhibits PTH at parathyroid gland

Answer 61

vitamin D

Question 62

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

Answer 62

vitamin D

Question 63

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

Answer 63

vitamin D

Question 64

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

Answer 64

vitamin D

Question 65

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

Answer 65

vitamin D

Question 66

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

Answer 66

FGF-23 (fibroblast growth factor 23)

Question 67

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

Answer 67

FGF-23

Question 68

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

Answer 68

FGF-23

Question 69

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

Answer 69

calcitonin

Question 70

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

Answer 70

calcitonin

Question 71

High during gestation and lactation: to protect maternal bones

Answer 71

calcitonin

Question 72

Stimulates OPG and inhibits osteoclast differentiation

Answer 72

estrogen

Question 73

increase osteoclast effect and decrease osteoblast effect; calcium wasting

Answer 73

glucocorticoids

Question 74

Prolonged ________therapy can lead to bone loss and osteoporosis

Answer 74

glucocorticoid