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Mammalian Physiology > Tissue and Bone Growth > Flashcards

Tissue and Bone Growth Flashcards

1
Q

4 types of bone

A

long, short, flat, irregular

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2
Q

diaphysis

A

main shaft of long bone. the hollow space in it is called the medullary cavity- which is filled with yellow marrow

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3
Q

function of diaphysis

A
  • the main shaft of long bones, to provide strong support without a lot of weight
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4
Q

ends of long bone, made with cancellous bone filled with marrow

A

epiphysis

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5
Q

function of epiphysis

A

to provide attachments for muscles and give stability to joints

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6
Q

layer of hayline cartilage that covers the articular surface of the epiphysis

A

articular cartilage

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7
Q

endosteum

A

thin epithelial membrane that lines the medullary cavity in long bone

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8
Q

medullary cavity

A

the hollow space in the diaphysis of long bone

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9
Q

dense white fibrous membrane that covers long bone is called

A

periosteum

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10
Q

function of the periosteum

A

contains cells that form and destroy cells, contains blood vessels and attaches tendons to bones

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11
Q

could long bones survive without periosteum

A

no, very essential for bone broth and survival

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12
Q

inner portion of short, flat and irregular bones

A

cancellous bone, with red bone marrow, covered by compact bone

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13
Q

where is red bone marrow found in irregular bones

A

inside the spaces of cancellous bone

- large amounts found in flat bones: found in ribs, pelvis and skull

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14
Q

group substance

A

the organic matrix secreted by bone cells–> collagen fiber, protein and polysaccharides
- this is the medium in which bone grows, nutrients diffuse and waste is excreted

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15
Q

are there osteons in cancellous bone

A

no, instead is has trabeculae- needle like bony spicules

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16
Q

difference between compact bone and cancellous bone

A

cancellous bone is spongy and consists of trabeculae, whereas compact has osteons

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17
Q

bone reabsorbing cells

A

osteoclasts (giant cells, multinucleate)

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18
Q

bone building cells

A

osteoblasts

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19
Q

osteoclasts are attached to the surface by

A

integrins

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20
Q

osteocyte

A

is a trapped osteoblast that is surrounded by bone matrix

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21
Q

RANK ligand (released by osteoblast to recruit osteoclasts)

A

is a protein expressed by osteoblasts. it binds to the RANK receptors on osteoclasts precursors. this interaction stimulates precursor to make them become active and resorbs bone

22
Q

what triggers RANK pathway

A

parathyroid hormone (PTH) from parathyroid gland, want to release calcium from stores

23
Q

what inhibits the RANK pathway and prevents bone resorption

A

estrogen

24
Q

what hormones control blood calcium levels

A

parathyroid hormone and calcitonin

25
Q

post menopause women tend to have a

A

negative calcium balance- more output

26
Q

parathyroid (PTH)

A

released when blood Ca levels are low

  • bone erosion- release calcium
  • enhance renal reabsorption of Ca
  • stimulates the release of calcitriol
  • which increases intestinal ca absorption
27
Q

calcitriol

A

increase cal reabsorption in intestine

28
Q

where does calcitriol come from

A

vitamin D

- with release of parathyroid hormone the kidneys convert 25-hydroxycholecalciferol to calcitriol

29
Q

what lowers blood calcium levels

A

calcitonin ( different from calcitRIOL)

30
Q

what acts opposite of parathyroid

A

calcitONIN

Calcitonin

31
Q

action of vitamin D on calcium regulation

A
  1. increase reabsorption in the tubules of kidney

2. increase amount of transporters in intestine ( more calcium)

32
Q

vit D stimulates

A

osteoblasts. to build more bone

33
Q

what does exercise stimulate

A

osteoblasts to secrete more collagen which makes bones stronger

34
Q

two mechanisms for bone formation

A
  1. intramebranou

2. endochondral

35
Q

intramembranous

A

does not begin with cartilage model

  • instead, just dense areas of mesenchymal cells differentiate and begin to lay down bone themselves
  • occurs within a CT membrane
36
Q

examples of intramembranous bone

A

flat bones, skull or jaw bone

37
Q

endochondrial bone development

A

mesenchymal cells migrate to site of bone, differentiate into chondrocytes–> very dense avascular mass, catalogue forms in the shape of bones

  • they die
  • then cartilage gets surrounded by periosteum, now it can develop and enlarge
  • osteoblasts that differentiate from inner collar of periosteum produce a hollow of bone
  • blood vessels enter the cartilage at the diaphysis
38
Q

which way do bones grow endochondrally?

A

ossification progress from the diaphysis towards each epiphysis–> this is how the epiphyseal plate remains/forms!!
- the epiphysis plate remains until the bone is totally done growing ( it keeps getiting pushed up)

39
Q

epiphyseal plate has ___ layers

A

4: top= resting, proliferating, hypertrophy, calcification –> diaphysis

40
Q

how do bones grow in diameter?

A

osteoclasts enlarge the diameter of the medullary cavity and osteoblasts from the periosteum build new bone around the outside of the bone

41
Q

how do bones grow in length ?

A

through the action of either endochondrial formation or intramembranous development –> formed from mesenchymal stem cells which either turn into chondrocytes which differentaite into osteoblasts or differentiate right into osteoblasts right away (as in flat bones)

42
Q

what does OPG do?

A

binds to RANKL, competitive inhibitor for RANK on precursor osteoclasts (cause less osteoclasts to be made- thereby limiting bone resorption)

43
Q

how is OPG made?

A

estrogen causes osteoblasts to product TGF-B, which casues them to produce OPG

44
Q

high levels of estrogen

A

= high levels of TGF-B = high levels of OPG = low levels of bone resorption and low calcium

45
Q

low levels of estrogen

A

= low TGF-B = low OPG= high osteoclast activity = breaking down bone -> this is why post menopause women are at high risk of osteoporosis (less estrogen)

46
Q

how to treat osteoporisis

A

raloxifene, calcitonin, estrogen replacement therapy, exercise

47
Q

what expresses RANK ligand

A

osteoblasts ( its like they are telling the precursors to become mature to remodel bone!) they release RANK ligand which bind to RANK on precursor osteoclasts

48
Q

after resorption of bone…

A

osteoblasts move back into the pit and start reforming the bone, some become embedded into the matrix become osteons, while other become new lining cells

49
Q

estrogen causes what?

A

osteoblasts to secrete TGF-B, which casues them to produce OPG- which block RANK

50
Q

increasing PTH has wat effect on the kidneys?

A

tells kidney to make more calcitriol from vitamin D, which results in more Ca+ absorbed from intestines ( calcitriol makes more transporters)

51
Q

low Ca2+ casues release of ___ to stiulate ______

A

PTH, osteoclasts, kidneys to make calcitriol, intestines to absorb more Ca+

52
Q

high blood Ca+ causes release of _____ to stimulate

A

calcitonin from the thyroid, to stimulate osteoblasts to make more blood and use calcium

Mammalian Physiology (17 decks)

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