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Med Prep > endocrine - Ca and phosphate homeostasis > Flashcards

endocrine - Ca and phosphate homeostasis Flashcards

0
Q

Bone cell type for production of matrix

A

Osteoblast

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1
Q

Circulating forms of calcium

A

Ionized - 50%
Protein-bound - 40%
Complexed with anion - 10%

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2
Q

Bone cell type for resorption of matrix

A

Osteoclasts

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3
Q

Hormones and minerals found in bones

A 
PTH
Vit D
Calcitonin
Calcium
Phosphorus
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4
Q

Predominant parenchymal cell type and a primary endocrine cell of parathyroid gland

A

Chief/principal cell

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5
Q

Larger, mitochondria-rich, eosinophilic cell type of parathyroid gland

A

Oxyphil cell

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6
Q

Major regulator of calcium and phosphorus metabolism

A

PTH

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7
Q

The most important effect of PTH is to increase/decrease plasma calcium level

A

Increase plasma calcium level

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8
Q

The most important effect of PTH is to increase plasma Ca level by

A

Stimulate bone resorption
Increase renal tubular reabsorption
Stimulate renal 1,25 dihydroxy- D synthesis

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9
Q

PTH decrease /increase plasma phosphate

A

Decrease plasma phosphate

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10
Q

PTH decrease plasma phosphate by

A

Inhibiting renal tubular phosphate reabsorption

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11
Q

Parathyroid cell type that secretes PTH

A

Chief cell

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12
Q

Primary target of PTH

A

Bone

Kidneys

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13
Q

PTH receptors

A

PTH1R (hPTH/PTHrP)
PTH2R
CPTH

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14
Q

Pty receptor that bonds both PTH and PTHrP

A

PTH1R

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15
Q

PTH receptor that activates adenylyl cyclase and PLC

A

PTH1R

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16
Q

PTH receptor that is abundant in bones (osteoblasts) and kidneys (prox and distal convoluted tubules)

A

PTH1R

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17
Q

PTH receptor that does not bind to PTHrP

A

PTH2R

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18
Q

PTH receptor that is found in brain, placenta and pancreas

A

PTH2R

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19
Q

PTH receptor that reacts with the carboxylate terminal rather than amino terminal of PTH

A

CPTH

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20
Q

Primary stimulating signal of PTH

A

Low circulating Ca level

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21
Q

Low circulating Ca level is sensed by principal cells thru

A

Ca-sensing receptor (CaSR)

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22
Q

High Mg level inhibits PTH

A

True

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23
Q

PTH stimulation

A 
Phosphodieasterase inhibitors 
Epinephrine
Dopamine
Histamine
Lithium
Thiazides diuretics
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24
Q

PTH inhibition

A

A-adrenergic agonists
Prostaglandins
Aluminum
Chromogranin

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25
Q

Mechanism of action of PTH in kidneys

A

Stimulates Ca reabsorption
Inhibits Pi reabsorption
Stimulates conversion to 1,25 dihydroxy vitamin D

26
Q

Vit D3

A

Cholecalciferol

27
Q

Vit D synthesis

A

7-dehydrocholesterol -(skin UV light)- cholecalciferol - (liver vitD 25-hydroxylase)- 25hydroxycholecalciferol -(kidney 1a-hydroxylase)- 1,25dihydroxyvitamin D

28
Q

Rate limiting enzyme in vit d synthesis

A

1a-hydroxylase (CYP1a)

29
Q

Secosteroid (class of steroid with 1 open cholesterol ring)

A

Vit D3

30
Q

Ergocalciferol, secosteroid produced in plants. Enters the liver for hydroxylation via portal circulation and chylomicrons

A

Vit D2

31
Q

Facilitates absorption of Ca in duodenum and jejunum

A

Vit d

32
Q

Percentage of active vit d that circulates as free steroid

A

0.4%.

Other binds to DBP from liver

33
Q

What kind of receptor is vit D receptor

A

Nuclear receptor

34
Q

Low Ca stimulates renal 1a-hydroxylase thru increased PTH

A

High Ca inhibits 1a-hydroxylase thru CaSR in proximal tubule

35
Q

Very active vit D preparation

A

Calcitriol

36
Q

Effect of calcitonin to phosphate and Ca level

A

Decrease Ca and decrease phosphate

37
Q

Effect of PTH to phosphate and Ca level

A

Increase Ca

Decrease phosphate

38
Q

Effect of vitD to phosphate and Ca level

A

Increase Ca

Increase phosphate

39
Q

Bone remodeling is regulated by

A

PTH

40
Q

Calcitonin is produce by what cell

A

Parafollicular C cell

41
Q

Calcitonin is regulated by

A

CaSR and high Ca level

42
Q

Calcitonin is primarily inactivated in what organ

A

Kidney

43
Q

Inhibits bone resorption

A

Calcitonin

As decreases Ca and Pi

44
Q

Useful histo chemical marker for MEdullary thyroid Ca

A

Calcitonin

45
Q

Calcitonin is expressed in

A

Osteoclast (inhibits bone resorption)

Nephrons (inhibits Ca and Pi reabsorption)

46
Q

Major stimulus of calcitonin

A

Hypercalcemia

47
Q

Normal calcitonin plasma level

A

10-20pg/mL

Any increase In plasma Ca by 1mg/dl will result to 2-10fold acute rise in calcitonin

48
Q

Calcitonin release is stimulated by

A

Vit D

Ingestion of food due to GASTRIN

49
Q

Inhibitors of calcitonin

A

Low vit D

Somatostatin

50
Q

Calcitonin excess does not produce hypocalcemia (MTC).

Calcitonin deficiency does not produce hypercalcemia (post total thyroidectomy for thyroid Ca )

A

Calcitonin plays a very minimal or negligible physiologic role in Ca and phosphate homeostasis

51
Q

Hyperparathyroidism is an excessive production of PTH that is usually due to single adenoma. It has high/low Ca and high/low Pi.

A

High Ca and low Pi

52
Q

High Ca and low Pi in hyperparathyroidism is due to

A

Bone demineralization
High GI Ca absorption
High renal Ca reabsorption

53
Q

Hypoparathyroidism is due to PTH and vitD deficiency. It has high/low Ca and high/low Pi.

A

Low Ca and high Pi

54
Q

The low Ca and high Pi in hypoparathyroidism is due to

A

Impaired GI Ca absorption
Decreased renal reabsorption
Decreased bone Ca mobilization

55
Q

Bone is not affected in hypoparathyroidism

A

True

56
Q

Rare familial disorder charac by tissue resistance to PTH.

A

Pseudo hypoparathyroidism

57
Q

There is high PTH secretion, low Ca and congenital defects of skeleton.

A

Pseudo hyperparathyroidism

58
Q

Mg and Ca in vit D deficiency

A

Low mg and Ca

59
Q

VitD deficiency leads to defective bone mineralization in adults

A

Osteomalacia

60
Q

VitD deficiency leads to defective bone mineralization in children

A

Rickets

61
Q

VitD deficiency leads to secondary increase in PTH

A

Osteoporosis

62
Q

Results in bone deformities due to increase bone resorption ff by increase bone formation.
It has high alkaline phosphatase, osteocalcin and urinary hydroxyproline.
It produces pain, bone deformation and bone weakness.

A

Paget’s disease

63
Q

As in chronic renal disease with high Pi and low Ca due to high PTH and low vit D

A

Renal osteodystrophy

Med Prep (52 decks)

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