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Clinical X-Ray Practicum > Quiz 1 > Flashcards

Quiz 1 Flashcards

1
Q

When is parathyroid hormone released?

A

Released due to low blood calcium

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2
Q

What does parathyroid hormone indirectly stimulate?

A

Osteoclastic bone breakdown

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3
Q

Parathyroid hormone increases what 4 things?

A
  • Renal Calcium absorption in the DCT and CD
  • Renal excretion of phosphate
  • Intestinal absorption of phosphate
  • Renal activation of Vitamin d to its active form
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4
Q

What does activated vitamin D do?

A

increases intestinal absorption of calcium

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5
Q

Which hormone activates Vitamin D ?

A

PTH

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6
Q

Physiological increases of PTH have been shown to do what?

A

Increases calcium in adipocytes

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7
Q

PTH excess may promote what? How? (review this article)

A

Weight gain

-by impeding catecholamine induced lipolysis

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8
Q

What do Parafollicular cells release?

A

calcitonin

-(a peptide hormone)

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9
Q

What stimulates calcitonin release?

A

Elevated blood calcium and gastrin

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10
Q

What does Calcitonin do regarding osteoblasts?

A

Calcitonin binds to and inhibits osteoclasts thus increasing osteoblastic activity

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11
Q

What two things does calcitonin increase?

A
  • Renal excretion of calcium

- Renal absorption of phosphate

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12
Q

What two diseases is calcitonin used in?Why?

A
  • osteoporosis
  • Pagets
  • inhibits bone pain
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13
Q

What peptide hormone may be used as a diagnostic marker in medullary thyroid cancer?

A

Calcitonin

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14
Q

Bisphosphonates have been shown to what?

A

Increase bone mineral density in patients with osteoporosis and osteopenia

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15
Q

What has been shown to reduce vertebral fracture rates with minimal change in bone density

A

Calcitonin

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16
Q

What has been shown to reduce bone pain associated with fractures?

A

calcitonin

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17
Q

How do androgens affect bone directly?

A

Via interactions with androgen receptors

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18
Q

How do androgens affect bone indirectly?

A

Via binding to ERalpha and ER beta after aromatization

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19
Q

What two things preserve trabecular bone?

How?

A
  • Androgens
  • Estrogens
  • By decreasing osteoclastogenesis after interacting with bone marrow osteoblast precursors and possibly osteoclasts
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20
Q

What do androgens and estrogens prevent?

A

Prevent osteoblast apoptosis

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21
Q

What do androgens and estrogens stimulate?

A

Osteoclast apoptosis

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22
Q

How do androgens exert their major effect on trabecular bone?

A

Local aromatization to estrogens

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23
Q

What mediates androgens effects on growth plate closure?

A

aromatization to estrogens and binding to ERalpha

24
Q

Androgens promote growth in what direction?

A

Radial

25
Q

Estrogens promote growth in what direction?

A

Longitudinal

26
Q

Why do female growth plates ossify more rapidly

A

Estrogen promoting longitudinal growth formation

27
Q

New thoughts on progesterone?

A

it is likely working through bone formation pathways to play a role in maintaining women’s bone and in osteoporosis prevention
-progesterone as co-therapy with antiresorptive agents may have promise

28
Q

Is glucocorticoid excess affect on bone good or bad?

A

Bad!

29
Q

What can glucocorticoids do to bone in excess?

A

reduce bone formation and restoration

  • causes a disorder of mesenchymal stroll cells
  • induces osteoporosis
30
Q

What are four factors that influence bone remodeling?

A
  1. ) Bone morphogenetic proteins (BMP)
  2. ) Wnt proteins (mammalian homologue of winglessness in drosophila)
  3. ) Insulin-like growth factor 1 (IGF-1)
  4. )Receptor activator of nuclear factor k-b(RANK) ligand
31
Q

What are Bone Morphogenetic Proteins (BMP)

-what is their mechanism of action?

A
  • BMP belong to family of transforming growth factor beta

- MOA: formation of new osteoblasts

32
Q

What are WNT proteins and what is their MOA?

A
  • Glycoproteins functioning through multiple pathways
  • MOA:
    1. ) specification of osteoblasts from chondrocytes
    2. ) enhanced formation of osteoblasts
    3. ) Enhanced survival of osteoblasts and osteocytes
33
Q

What is insulin-like growth factor 1 (IGF-1) and what is its MOA?

A
  • in charge of bone production stimulated by parathyroid hormone
  • MOA: osteoblast differentiation and prevention of osteoblast apoptosis
34
Q

What is Receptor activator of nuclear factor k-B (RANK) Ligand and what is its MOA?

A
  • Protein produced by osteoblasts

- MOA: promotes osteoclast activation and favors bone reabsorption

35
Q

Hypothyroidism can cause what on bones?

A

impaired bone formation and growth retardation

36
Q

What does thyrotoxicosis (surpassed tsh) result in?

A

accelerated growth, advanced bone aage and decreased bone mass

-leads to increased risk of osteoporotic fracture

37
Q

What does recent research show that TSH may be?

A

a negative regulator of bone turnover acting via the TSH receptor on both osteoblasts and osteoclasts

38
Q

New research shows that TSH deficiency could be responsible for what?

A

skeletal loss seen in thyrotoxicosis

39
Q

What is the only thing that responds to TSH regarding bone?

A

Osteoclasts

40
Q

What does the lack of cAMP response to TSH or TSHrab in mature osteoclasts suggest?

A
  1. ) TSHR acts via an alternative pathway or
  2. ) TSH effects on osteoclast numbers and resorption pits reflect its early actions on progenitor cells to regulate osteoclast recruitment and differentiation
41
Q

What does growth hormone do?

A

Stimulate growth of bone, cartilage and connective tissue

-increases the number of cells (ex.muscle and bones)

42
Q

What does the family of polypeptide called somatomedin do?

A

mediates the effects of growth hormone on skeletal growth?

43
Q

What is necessary for normal osteogenesis?

A
  • Thyroid hormone

- Insulin

44
Q

What does Insulin do in regards to osteogenesis?

A

Increases cytoplasmic growth

45
Q

What does thyroid hormone required for?

A

Full effect oh growth hormone on DNA replication

46
Q

Growth hormone stimulates what?

A

proliferation of human osteoblasts

47
Q

What did studies show about IGF-1 and II?

A

they exerted proliferative effects on both Human osteoblast like cells (HOB) and human marrow stromal cells (HMS)

48
Q

Studies showed that co-stimulation of IGF-I and II with GH exhibited what?

A

synergism in enhancing the proliferative response

49
Q

What is the active form of vitamin D?

A

1,25(OH)2D3

50
Q

What is vitamin D responsible for?

A

absorption of calcium from the gut

-acts indirectly by increasing serum calcium levels thus reducing effect of PTH on bone

51
Q

Where is Vitamin D synthesized?

A
  • Skin
  • Liver
  • Kidney
52
Q

Vascular calcification, angiogenesis and vascular cell migration is regulated by what protein?

A

vitamin k dependent protein

53
Q

What is Matrix Gal Protein (MGP)

A

Type of Vitamin K dependent protein that inhibits osteogenic factors thereby inhibiting vascular and soft tissue calcification

54
Q

What are the Normal T Score Findings

What do they mean

A

T>-1.0

Low fracture risk

only give lifestyle advice

55
Q

T= -1.0 to -2.5

A

Above Average

Possible osteopenia

HRT in women, possible vitamin D

56
Q

T < -2.5

A

Osteoporosis
High fracture risk

give bisphononates

Clinical X-Ray Practicum (3 decks)

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