11/17 Histo of Bone Flashcards Preview

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Flashcards in 11/17 Histo of Bone Deck (81):
1

The function of bone:

Levers for movement. support and protection. hematopoiesis in marrow, store and regulate serum levels of calcium and phosphate.

2

The two types of bones depending on the density

spongy bone and compact bone....

3

Describe the outer wall of bones

compact or cortical bone

4

what type of bone is the interior of bone made of?

trabecular (spongy, cancellous) bone and marrow

5

I am looking really close at compact and spongy bone samples...how can I distinguish the two? (microscopic scale)

compact and trabecullar bones are identical at the microscopic level...so good luck buddy!

6

the covering of bone surfaces...

connective tissue: periosteium on the outside and endosteum on the internal surface and long bones have Articular cartilage at the joints

7

Source of nutrition and progenitor cells for making bone:

periosteum and endosteum

8

found on the ends of long bones:

articular cartilage (no periosteum

9

two types of bone cell lineages:

undifferentiated mesenchymal cells and hematopietic stem cells

10

What is the family lineage of bone cells that come from Undiferentiated mesencymal stem cells?

Messenchymal cells gives rise to Osteoprogenitor cells called an osteoblast that gives rise to osteocyte!

11

What is teh family lineage of bone cells that come from hematopoietic stem cells.

Hematopoietic stem cells produce monocytes that produce Osteoclasts (they also prodcue macrophages of course so osteoclasts and macrophages are like siblings...:-)

12

the progenitor cells in periosteum and endosteum:

osteoprogenitor cells (preosteoblast)

13

what do osteoprogenitor cells produce:

osteoblasts

14

Can osteoprogenitor cells move or divide?

yes they proliferate and circulate!

15

how could osteoblasts be connected to calcified vessels

they may circulate in and make cells that make calcium... thus the migration of calcium from the skeleton to the vessels!

16

what do osteoblasts do?

bone-forming cells that secrete osteoid (ECM) mineralize the matrix and do NOT divide

17

derived from osteoblasts and surrounded by bone matrix

osteocytes

18

the opening where the osteocytes sit

lucunae between layers (lamellae) of adult bone.

19

the principal cell in adult bone 95%

osteocytes

20

HOw is the ostyocyte like a spider?

they put out little legs from the lacunae, through canaliculi to form gap junctions with other cells around them.

21

How do ostyocytes communicate, and maintain the matrix of cells in the bone

form continuous system of cells thorghout the bone via gap junctions in canaliculi between cells.

22

what do the osteocytes do?

maintain the matrix: sense stress, communicate with other cells: THE CELLS THAT MAKE AND MAINTIAN BONE

23

The cells that take bone apart (resorb bone)

the osteoclasts

24

multinucleate cells that are derived form macrophages in the bone marrow.

osteoclast

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the space that an osteoclast forms on the surface of bone

Howship's lucunae

26

what happens in the howship's lacunae?

Oseoclast excretes acid and lysosomal enzymes that take bone apart and release calcium

27

what regulates the actions of osteoclasts?

indirectly by parathyroid hormone (up regulate) and perhaps directly by calcitonin

28

The purpose of osteoclasts

bone turnover and Ca2+ regulation

29

what is the principle organic components of bone matrix?

collagen type I and GAGs and proteoglycans and a bunch of glycoproteins

30

what will all of the glycoproteins in the bone matrix do?

promote mineralization, serve as hormones as well!

31

what is an example of hormone from bone...

osteocalcin released when bone is turned over and is connected to type II diabetes

32

Inorganic components of bone:

Hydroxyapatite (calcium and phosphate in a molecule) and trace minerals

33

How do we develop and make bone?

there are two different paths of development and each one will use the same two steps to make the bone and we end up with two different types of bone so...2 by 2 by 2 makes bone! (intramembranous or Endochondral formation makes 1. primary=woven and 2. secondary bone=lamellar, to end up with 1. Compact Cortical bone or 2. Spongy Cancellous Trabecular bone

34

The two processes of making bone

osteoblasts begin to make bone in : 1. Loose connective tissue in a process called intramembranous bone formation. -or- 2. Hylanine cartilage that makes a matrix and has just died in a process called endochondral bone formation.

35

what is bone formation on loose connective tissue?

intramembranous bone formation

36

bone formation on cartilage matrix

endochondral bone formation

37

the two steps in bone formation

1. primary bone = woven bone; 2. Secondary bone = Lamellar bone

38

what is woven bone

random collagen fiber orientation: temporary bone that is removed or replaced with secondary bone

39

what is secondary bone

parrallel collagen fibers arranged in layres, can become permanent but will be continuously remodeled.

40

The two types of mature bone:

compact bone = cortical bone; Spongy bone=cancellous bone=trabecular bone

41

what is trabecular bone

thin bone that can be nourished form outside

42

what is compact bone

thick bone that requires internal blood supply: osteons

43

the microscopic organization of primary (woven bone)

randomly oriented collagen fibers: an orientation called trabecular

44

when does Primary (woven) bone appear?

appears during development or during repair!

45

What is the fate of primary bone?

to be replaced by mature lamellar bone or removed to make marrow cavity.

46

Describe the microscopic organization of secondary bone

Lamellar bone is composed of layers of matrix that are parallel to each other, oriented 90 degrees from fibers in adjacent lamellae. (like a sheet of plywood, or a skateboard deck!)

47

Where are the osteocytes in lamellar bones?

they are in lacunae between the lamellae layers! (stuck in the glue between layers of the skateboard deck!)

48

The Microscopic orientation of all mature adult bone:

Lamellar.

49

The composition of most compact bones:

they consists of osteons, or haversian systems in long lines around canals of nerves blood and lymph called haversian canals.

50

lamellae of bone surrounding individual haversian canals

Osteons

51

the contents of osteons

Layers of mature secodary bone wrapped around haversian canals that contain nerves, blood vessels and lymphatics

52

the vertical connections between seperate lines of haversian canals

volkmanns canals

53

if it is thick enough, trabecular spongy bone bone can also have..

osteons

54

Enclose osteons, and are close to blood vessels in connective tissue coverings

circumferential lamellae

55

The canals in the middle of Osteons

haversian canals

56

the canals that connect haversian canal

volkmann canal

57

the space between osteons (triangular space)

intersitial lamella

58

the tissue between two osteons that are a little darker staining

Cement lines

59

The type of bone development that is responsible for the development of flat bones of skull and mandible

intramembranous ossification

60

How do long bones grow in diameter?

in the pericardium of the cartilage, the osteoblasts invade and begin to calcify the tissue and kill the cartilage and the osteoclasts then chew up the bones in the middle and the osteoblasts build it on the outside. This is called: INTRAMEMBRANOUS OSSIFICATION

61

how can you make a bone wider and not make it heavier?

add on the outside and chew up on the inside (osteoblasts and osteoclasts) or INTRAMEMBRANOUS OSSIFICATION

62

How do long bones grow longer?

they grow through endochondral ossification: replacement of cartilage model with bone! the cartilage continues to grow and is alive under the developing bone, creating a secondary center of ossification above the living cartilage model now called the epiphyseal growth plate.

63

The layers of the epiphyseal growth plate

the resting cartilage, the proliferation zone, the maturation/hypertrophy zone, the calcification zone, and the ossification zone! (transition from cartilage to ossified bone!)

64

Does the bone in the epiphyseal growth plate get remodeled?

yes deffinetly! it is being deposited and removed simultaneously in the growth plate! (osteoclasts / osteoblasts at work)

65

Why do we every stop growin?

Systemic growth hormone production stops and chondroblast produced factors are lost as chondroblast proliferation stops leading to the closure of the epiphyseal growth plate when all of the cartilage becomes bone!

66

bone growth will continue until closure of...

the epiphyseal growth plate

67

how can the movement and stress on a bone affect growth?

the physical forces influence bone modeling that is constantly taking place with osteoclast/blasts

68

how much bone is replaced in an adult?

about 10% of total bone is replaced yearly.

69

the way that bone is replaced

osteoclasts degrade old osteons and osteoblasts generate newe osteons

70

how is fracture repaired?

blood clot soon invaded by myofibroblasts, chondroblasts, osteoblasts; soft callus formed (loose CT and hyaline cartilage) then intramembranous and endochondral bone formation happens initially; then hard callus of primary woven bone and then remodeled to lamellar bone

71

what is the overriding factor that balances bone resorption in the body?

calcium mobilization

72

what is the condition where the bone formation balance doesn't match resorption?

osteoporosis

73

what is the cause of osteoporsis

activity of osteoclasts outpaces the now much lazy osteoblasts

74

what happens in osteoporosis in bone?

decrease in bone mass with composistion of bone matrix is normal.

75

factors associated with osteoporosis?

aging, decreased estrogen in postmenopausal women, inactivity (space flight)

76

decreased bone resorption due to defective osteoclasts:

osteopetrosis

77

the results of osteopetrosis

reduced marrow cavity, decreased blood formation, anemia and infection.

78

what is the deffect in osteoclasts in osteopetrosis?

no ruffled border so can't make the little cacoon

79

disease with loss of articular cartilage

osteoarthritis (OA)

80

what happens in osteoarthritis?

erosion of articular cartilage that reduces joint function: leads to bone remodeling, pain, and loss of activity.

81

Describe the change in the joints that may lead to osteoarthritis?

the stable chondrocytes in the articular surface change and start acting more like transient growth cartilage, they proliferate and become Hypertrophic-like, turning over matrix more quickly. this leads to worse damage.