block 5 lecture 5 bone metabolism Flashcards

(58 cards)

1
Q

what percentage is organic bone material?

A

40%

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

what percentage is inorganic bone material?

A

60%

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

what is the organic materials of bone?

A

type 1 collagen and non-collagenous protein

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

what is the inorganic portion of bone?

A

calcium hydroxyapatite

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

what is trabecula bone?

A

cancllous and spongy bone

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

what are osteoclasts?

A

multi nucleated cells formed from many monocytes

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

what can increase the resorption of bone by an osteoclast?

A

bigger osteoclasts perform more aggressive resorption of bone

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

how do osteoclasts adhere to the bone matrix?

A

by forming lipid like adhesions and express strong intergrin interactions

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

what do osteoclasts do?

A

secrete enzymes and acids to degrade matrix

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

what happens to degraded bone material by osteoclasts?

A

shoots up through apical membrane and removed from the cell

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

what are the osteoclast resorption pits called?

A

howships lacuna

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

what are osteoblats?

A

mononucleated stromal cells

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

what do osteoblasts come from?

A

mesenchymal cells

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

what do osteoblasts do?

A

mineralize bone matrix to replace removed bone

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

what do osteoblasts form into?

A

osteocytes

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

what do the extesions of osteocytes make connections with?

A

the bones surface and other osteocytes

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

what do the processes of osteocytes act as?

A

mechnosensors

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

hat stops osteoclasts resorbing?

A

reversal stage

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

what is the matrix that osteoblasts lay down?

A

type 1 collagen and non colagenous protein

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

what is the bone matrix called when it is initially laid down?

A

osteoid

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

what are some signals involved in bone growth?

A

parathyroid hormine, vitamin D, calcitonin, growth hormone, growth factors, oestrogen, cytokines

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

what is the calcuim resevoir?

A

skeleton

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

what are the three fractions of calcium in serum?

A

ionised calcium, protein bound calcium and complexed calcium

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

what is Ca2+ maintained by?

A

PTH, Vitamin D, cacitonin

25
where do you find phsphate?
skeleton and extracellular fluid
26
what are the three fractions of phsophate in serum/
ionised phosphate | protein bound phophate and complexed
27
what is phsphate metabolism regulated by?
PTH
28
where can you recieve vitamin D?
in the skin, digestion
29
in the skin how is vitamin D procuced?
7-dehydrocholesterol is converted by UV light to vitamin D
30
how is vitamin D activated?
2 rounds of hydroxylation
31
where does the first hydroxylation of vitamin D occur?
liver
32
where does the second hydroxylation of vitamin D occur?
kidney
33
what type of vitamin D is responsible for most biological mechanisms?
principle hormonal form
34
what is the production of vitamin D regulated by?
PTH
35
what is the production of vitamin D inhibited by?
elevated serum calcium or phosphate
36
what doe vitamin D do?
increases calcium and phosphate absorption from intestines mobilised calcium and phophate from bone induces marrow monocytes to increase production of osteoclasts to promote resorption
37
what seceretes PTH?
parathyroid gland
38
what can PTH stimulate?
osteoclast resroption decresases renal calcium secretion increases renal production of vitamin D
39
what is parathyroid hormone related protein produced by?
normal and malignant cells
40
what is PTHrP required for?
development, regulator of proliferation and mineralisation of chondrocytes
41
what s calcitonin?
small poly peptide
42
what releases calcitonin?
parafollicular cells of the thyroid
43
what induces the release of calcitonin?
high plasma calcium levels
44
what does calcitonin do?
reduces bone resorption by activating calcitonin receptors expressed by osteoclasts
45
physiology of calcium metabolism to increase?
low calcium in circulation is detected by parathyroid gland, PTH is secreted, PTH and vitamin D increases the mobilisation of Ca into circulation
46
physiology of calcium metabolism to decrease?
calcium is detected by thyroid C cells, which increases the secretion of calcitonin, which targets osteoclats to limit resrption and decrease calcium in circulation
47
how does oestrogen affect bone metabolism?
reduce resorption by inhibiting osteoclastogenesis and inhibiting osteoclast function
48
how does androgens affect bone metabolism?
low levels means low bone density in men | they target osteoclasts
49
what are the causes of hypercalcium?
primary hyperthyroidism, malignancy, immobalisation, vitamin D toxicity
50
what is primary hyperthyroidism?
excessive secretion of PTH
51
what causes primary hyperthyroidism?
solitary adenoma of parathyroid glands
52
what are the symptoms of primary hyperthyroidism?
excessive skeletal erosion, kidney stones
53
causes of hypocalcemia?
renal failure, vitamin D defficiency, prematurity (immture vitamin D metabolism, immature parathyroid gland)
54
what is osteomalacia caused by?
vit D defficiency, malabsorption, renal disease, lack of sunlight, anticonvulsants inhibit vitamin D synthesis
55
osteomalacia symptoms?
bone pain around hips, muscle weakness, alavated alkaline phosphatase levels, decreased mineralisation, long bones bowing
56
what is osteoporosis?
net loss of bone mass and decreasd bone mineral density
57
in what type of person is osteoporosis common?
post menopausal woman, elderly, inactive
58
treatment of osteoporosis?
calcium supplementation, hormone replacement therapy, bisphosphates, calcitonin, selective estrogen receptor modulators