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Endocrinology > Hormonal regulation of calcium and phosphate metabolism > Flashcards

Hormonal regulation of calcium and phosphate metabolism Flashcards

1
Q

Two primary souces of circulating Ca and Pi

A

Diet and skeleton

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2
Q

The primary process of removal of Ca and Pi from blood

A

Renal excretion and bone formation

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3
Q

Two hormones that regulate intestinal absorption of Ca and Pi and release of Ca and Pi into circulation after bone formation

A

Calcitriol (1,25-dihydroxyvitamin D) and PTH (parathyroid hormone)

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4
Q

Forms in which circulating Ca exist

A

Free ionized Ca, protein-bound Ca, Ca complezed with anions

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5
Q

The ionized form of calcium is tightly regulated. T/F

A

T

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6
Q

The ionized form of calcium makes up how much of total circulating calcium?

A

50%

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7
Q

Most circulating Pi is in which form?

A

Free ionized form

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8
Q

PTH and calcitriol are refered to as calciotrophic hormones. T/F

A

T

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9
Q

PTH is secreted by which gland?

A

Parathyroid glands

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10
Q

Predominant parenchymal cell type in parathyroid glands

A

Principal (chief) cell

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11
Q

Primary hormone that protects against hypocalcemia

A

PTH

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12
Q

Primary targets of PTH

A

Kidneys and bone

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13
Q

What type of hormone is PTH

A

Protein/peptide

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14
Q

Prepro-PTH to pro-PTH is processed in which organelle?

A

RER

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15
Q

Pro-PTH to PTH is processed in which organelle?

A

Golgi apparatus

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16
Q

Primary signal that stimulates PTH secretion

A

Low circulating Ca

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17
Q

Which part of the parathyroid senses extracellular Ca?

A

Ca-sensing receptor (CaSR) in the parathyroid chief cell

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18
Q

Increasing amounts of extracellular Ca bind to the CaSR and activate signaling pathways that (inhibit/stimulate) PTH secretion

A

Inhibit

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19
Q

PTH is secreted as an 84-amino acid polypeptide. T/F

A

T

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20
Q

CaSRs are located in which cells?

A

Parenchyma (chief) cells of parathyroid glands

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21
Q

PTH production is regulated at the level of gene transcription by a calcium reponse element within the promoter of the PTH gene. T/F

A

T

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22
Q

The active form of vitamin D

A

1,25-dihydroxyvitamin D

23
Q

What type of hormone is vit D?

A

Steroid

24
Q

What type of steroid is vit D3?

A

Secosteroid

25
Q

The first hydroxylation of vitamin D to yield 1,25-dihydroxyvitamin D occurs in which organ?

A

Liver

26
Q

The second hydroxylation of vitamin D yield 1,25-dihydroxyvitamin D occurs in which organ?

A

Kidney

27
Q

How does vitamin D and its metabolites circulate the blood?

A

They are bound to vitamin D-binding protein (DBP), bound to other proteins or circulate as free hormones

28
Q

Receptor for calcitriol

A

Nuclear vitamin D receptor (VDR)

29
Q

The parathyroid hormone primarily mediates the following physiological effect except:

A. Increased bone resorption
B. Increased renal tubular reabsorption of calcium
C. Increased intestinal absorption of calcium
D. Acid-base balance

A

D

30
Q

Transport channel that allows Pi to be absorbed by the jejenum

A

Na-Pi cotransporter (NTP2)

31
Q

A large amount of Ca and Pi are stored in which organ?

A

Bone

32
Q

The destruction of preformed bone with the release of Ca, Pi and hydrolyzed fragments of the osteoid into the blood– what is this process called?

A

Bone resorption

33
Q

New synthesis of osteoid at the site of resorption and subsequent calcification of the osteoid, primarily with Ca and Pi from blood– what is this process called?

A

Bone formation

34
Q

Bone remodeling involves these two processes

A

Bone formation and resorption

35
Q

Two major classes of cells involved in bone remodeling

A

Osteoclasts and ostaoblasts

36
Q

Cells that promote the formation of bone

A

Osteoblasts

37
Q

Cells that promote the resorption of bone

A

Osteoclasts

38
Q

PTH promotes osteoclast activity, but the PTH/PTHrP receptors are on osteoblasts. T/F

A

T

39
Q

The primary endocrine regulator of bone remodeling in adults

A

PTH

40
Q

Regulation of bone remodeling by PTH requires normal levels of 1,25-dihydroxyvitamin D. T/F

A

T

41
Q

Which organs express VDR?

A

Small intestines, bone, kidney, and parathyroid gland

42
Q

When vitamin D is deficient, Ca-PTH secretion curve shifts to (right/left). Meaning?

A

Right

Normal calcium levels become less effective in supressing PTH secretion, and elevated PTH levels and increased bone turnover result.

43
Q

Which bone cells express VDR?

A

Osteoblasts

44
Q

This pair of parathyroid glands come from the 3rd pharyngeal pouch

a. superior
b. middle
c. inferior
d. nota

A

C

45
Q

Which ligand results in osteoclastogenesis?

A. PTH
B. RANKL
C. MCSF
D. AOTA

A

D

46
Q

True of parathyroid gland

A. Arise from 3rd pharyngeal pouch
B. Arise from 4th pharyngeal pouch
C. Lies in the capsule of thyroid gland
D. AOTA

A

D

47
Q

Which of the following pairs of hormone and function is correctly paired?

A. Increase in metabolic rate and temp- ADH
B. Growth and dev’t- Glucagon
C. Maintenance of blood Ca2 Level- PTH
D. AOTA

A

C

48
Q

Which among the following is/are true?

a. 50% of calcium serum is ionized
b. 40% of calcium serum is complexed
c. 10% of serum calcium is protein bound
d. AOTA

A

a

49
Q

Which of the following statements about ca is true?

a. better to measure ionized rather than total ca because the former is the physiologically active form
b. Ca is transported via primary and secondary processes out of the cell
c. metabolic alkalosis increases ca binding to protein
d. AOTA

A

d

50
Q

Decreases calcium and phosphate absorption

a. calcitonin
b. PTH
c. PTH rp
d. vitamin d
e. none of the above

A

a

51
Q

Increases serum Ca levels in patients with malignancies

a. calcitonin
b. PTH
c. PTH rp
d. vitamin d
e. none of the above

A

b

52
Q

chronic renal failure will cause increase in this hormone

a. calcitonin
b. PTH
c. PTH rp
d. vitamin d
e. none of the above

A

b

53
Q

From the follicular cell into lumen

a. calcitonin
b. PTH
c. PTH rp
d. vitamin d
e. none of the above

A

e

Endocrinology (6 decks)

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