Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

LOCO 2 > Bone Metabolism > Flashcards

Bone Metabolism Flashcards

1
Q

How do osteoclasts appear on a slide

A

Multinucleated
Large
Sparse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do osteocytes do

A

Determine the status of piece of bone, decide whether it needs removal and remodelling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What cells are immature osteocytes

A

Osteoblasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What type of bone marrow makes up the majority at birth

A

Red

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where does red bone marrow remain

A

Spongy bones of vertebrae, ribs, sternum, cranium and epiphyses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Name the 2 overall types of bone

A

Lamellar

Woven

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

2 types of lamellar bone?

A

Cortical/ compact

Cancellous/ trabeculae/ spongy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What % of adult bone mass is cortical bone

A

80

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the purpose of the Haversian canal system

A

All columns form around the outside so weight pushes on these columns
Deals with stress that comes from above

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which bone type has greater surface area? By how much?

A

Trabecullae bone 10* bigger surface area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When is woven bone used

A

Fracture healing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is collagen laid down in woven bone and what is the consequence of this

A

Randomly laid down collagen, so weaker structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What % of bone is organic

A

35-40%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What type of collagen makes up bone

A

Type 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 3 organic components of bone

A

Type 1 collagen
Proteoglycans
Growth factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What type of strength do proteoglycans provide

A

Compressive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the non organic components of bone

A

Calcium hydroxyapatite

Water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe how calcium hydroxyapatite coats the collagen

A

In blocks, leaving gaps of exposed collagen to ensure there is some bendability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are osteoclasts derived from

A

Haemopoietic stem cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are osteoblasts derived from

A

Osteoprogenitor cell (mesenchymal stem cell)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What structure enables osteocytes to detect any bends

A

Branches

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the overall signal for bone remodelling

A

Osteocyte death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What bone type is quicker to form

A

Trabecular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why does trabecular bone form faster than cortical

A

Larger surface area

Responds to stresses on the bone quicker

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Give 2 reasons for bone remodelling

A
  • Renews bone before deterioration

- Redistributes bone matrix along mechanical stress lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is sclerostin

A

A glycoprotein that inhibits bone formation by osteoblasts. Secreted by osteocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What inhibits sclerostin release

A

PTH and mechanical stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What increases sclerostic release

A

Calcitonin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is sclerosteosis

A

A mutation in the sclerostin gene causes autosomall recessive disorder characterised by bone overgrowth

30
Q

What is romosozumab

A

An antibody to sclerostin currently being trailed as a way to increase bone density

31
Q

Describe the role of osteoclasts in bone remodelling

A
  • Crawls across surface seeking out damage
  • Attaches to bone in leak proof seal
  • Releases protein digesting enzymes to break down collagen
  • Releases acid to dissolve bone minerals
32
Q

What ph is required to dissolve bone minerals

A

5

33
Q

What happens to the calcium broken down/ released by osteoclasts

A

Cross osteoclast to exit into the interstitial fluid

34
Q

What happens in bone remodelling once old bone has been destroyed

A

New osteoblast produced, moving into gap where osteoclast was
Secrete collagen and protein matrix, becomes embedded and surrounded
Fill lacuna with osteoid

35
Q

At what stage does new osteoid become mineralised

A

After about a week

36
Q

3 phases of bone remodelling

A

Rest
Resorption
Formation

37
Q

State the distribution of calcium in the body

A

99% skeleton
1% cells, blood and body
0.1% ECM

38
Q

What are normal serum calcium levels

A

2.2-2.6mmol/L

39
Q

How much free ionised calcium should there be in the body

A

1.0-1.25mmol/L

40
Q

What 3 things does maintenance of normal serum calcium depend upon

A

Intestinal absorption
Renal excretion
Skeletal mobilisation

41
Q

What is the RDI of calcium

A

500-1300mg

42
Q

How much calcium is secreted by the kidneys a day

A

200mg/day

43
Q

How much calcium is secreted by the gut a day

A

600-800/day in stools

44
Q

Describe the distribution of phosphate in the body

A

80-90% in skeleton

10% plasma

45
Q

What are normal plasma concentrations of phosphate

A

0.8-1.5mmol/L

46
Q

What hormone is used to modulate absorpton and excretion of phosphate and calcium

A

Parathyroid hormone

47
Q

What is the stimulus for PTH release

A

Low plasma calcium levels

48
Q

How does PTH act upon the kidney

A

Promotes calcium reabsorption and phosphate excretion

49
Q

How does PTH act on the bone

A

Calcium reabsorption increasing the number and activity of osteoclasts

50
Q

How does PTH increase nimber and activity of osteoclasts

A 
Osteoblasts have PTH receptor
Receptor is activated
Osteoblasts produce RANKL
Osteoclasts have RANKL receptors
Number and activity increases
51
Q

What is the effect of PTH of 1,250dihydroxyvitamin D synthesis

A

Increases it

52
Q

How does 1,25dihydroxyvitamin D affect calcium metabolism

A

Increases calcium absorption from the gut

53
Q

What molecules are required for osteoclast formation

A

RANKL and M-CSF

54
Q

What cells produce RANKL and M-CSF

A

Osteoblasts and stromal cells

55
Q

What does RANKL stand for

A

Receptor activator of nuclear factor kappa b ligand

56
Q

What does M-CSF stand for

A

Macrophage colony stimulating factor

57
Q

What is OPG

A

Osteoprotegrin

This is a decoy receptor for RANKL

58
Q

What expresses ephrin B2 ligand

A

Osteoclasts

59
Q

What expresses ephB4 receptor

A

Osteoblasts

60
Q

What is the effect of PTH on ephrin B2

A

Increases ephrinB2 expression

61
Q

Does oestrogen stimulate or inhibit RANLK

A

Inhibit

62
Q

When is calcitonin released

A

When serum calcium >2.25mmol/L

63
Q

3 effects of calcitonin release

A
  • Inhibits osteoclast differentiation and activity
  • Increased calcium excretion from kidney
  • Inhibits calcium absorption by intestines
    (opposite PTH)
64
Q

Where do we get vit D from

A

Diet

UV light

65
Q

What is normal daily requirement for vitamin D

A

400IU/ day

66
Q

Where is the active form of vitamin D made

A

Kidney

67
Q

What is the role of vitamin D in bone formation and remodelling

A

Prepares the ECM for mineralisation by produces pro-collagen type 1 and producing alkaline phosphatase matrix vesicles

68
Q

How does oestrogen effect calcium metabolism

A
  • Increased absorption in gut
  • Decreased reabsorption in bone
  • Inhibits osteoclasts
69
Q

What disease, common at menopause, is caused by decreased oestrogen or prolonged steroid use

A

Osteoporosis

70
Q

What is the effect of glucocorticoids on calcium metabolism

A

Decreased absorption in gut

Increased reabsorption/ decreased formation in bone

71
Q

What hormone may be used to treat menopausal osteoporosis

A

Progesterone

LOCO 2 (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions