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Anatomy > Bone > Flashcards

Bone Flashcards

1
Q

What is bone tissue

A

-specialized CT with mineralized matrix and cells ( osteoblasts, osteoclasts and osteocytes )

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2
Q

Functions of Osseous tissue

A
  • provide solid framework for the body
  • provide attachments for muscle and tendons
  • converts skeleto-muscular energy into movement
  • protects vital organs
  • calcium reservoir
  • blood formation occurs in bone marrow
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3
Q

Osteoblasts origin

A

-mesenchymal stem cells from the mesoderm

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4
Q

Osteoblasts function, type of secretion and where found

A
  • synthesize and secrete matrix vesicles
  • secrete calcium hydroxyapatite to calcify matrix
  • proteoglycans ( osteonectin - bind cells to ecm )
  • collagen 2

-found at surface of bone matrix

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5
Q

Shape of osteoblasts and how they connect to each other

A
  • cubodial

- adherent and gap junctions

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6
Q

What happens to osteoblasts as they mature

A
  • die by apoptosis ( major pathway )
  • differentiate into osteocytes
  • flatten and become bone lining cells
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7
Q

Lacunae and canaliculi

A
  • cavities in matrix in which osteocytes are trapped

- dendritic like extensions of osteocytes and which extend into matrix

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8
Q

How does bone mineralization occur

A
  • after Osteoid has been secreted
  • osteoblasts secrete vitamin k dependent osteocalcin which binds to Ca2+ ions and increase conc of mineral locally
  • also secrete matrix vesicles rich in alkaline phosphate and enzymes
  • the enzymes hydrolyze phosphate from macromolecules and increase conc locally
  • the matrix vesicles serve as foci for crystal formation which grow and more minerals are secreted and embedd collagen in it forming matrix
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9
Q

Osteocytes how they form and function

A

-by osteoblasts surround by matrix they secrete

  • maintain matrix
  • serve as detectors of stress and cracks in bone
  • trigger remedial functions in other cells
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10
Q

Function of canaliculi

A
  • exchange of metabolites from vessels hi each other and matrix
  • communication through gap junctions attaching canaliculi
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11
Q

Osteoclasts how they form and structure

A
  • osteoblasts and other bone marrow cells secrete RANK Ligand which binds to rank receptors on monocytes
  • this induces a signaling cascade stimulating the precursor to fuse together

-large motile and multi nucleated

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12
Q

Function of osteoclasts

A

Bone resorption during remodeling or to release Ca2+ into blood stream

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13
Q

Howship / resorption lacunae

A

-enzyme etched depressions occupied by osteoclasts during bone resorption

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14
Q

What is bone remodeling and function

A

-replaced of bone through resorption with new bone

  • remove brittle old bone
  • repairs micro cracks
  • repairs fractures
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15
Q

What is resorption

A

-when inorganic matter of bone is dimineralized and organic part is degraded

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16
Q

What is a characteristics of osteoclasts

A

-the enzyme TRAP tartrate resistant acid phosphatase

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17
Q

Origin of osteoclasts and they precursor

A

Hematopoietic in origin

-precursor is monocyte

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18
Q

What hormones control osteoclasts formation

A
  • vitamin D3
  • parathyroid
  • cytokines ( IL-1 , IL-6 )
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19
Q

How do osteoclasts prepare for resorption

A
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20
Q

Describe bone respiratory

A
  • osteoclasts at ruffled border attach to membrane using proteins forming resorption compartment
  • pumps protons from H2CO3 into inorganic matrix to demineralize it forming howship lacunae and exposes organic part
  • organic part degraded by enzymes and vesicles phagocytosis then endocytized
21
Q

Effect of bone resorption

A

Ca2+ released into blood steam

-old bone degraded

22
Q

Proteins which attach to membrane from osteoclasts

A

Osteopontin

-bone sialoprotein BSP

23
Q

What is sealing zone and use

A
  • area between osteoclasts and matrix

- produces conducive micro environment for resorption

24
Q

Enzymes which degrade organic part of bone

A

Acid phosphatase

-cathepsin K

25
Hormones which affect bone resorption and where they come from
- RANKL helps osteoclasts form and mature - osteoprotegerin from osteoblasts bind with RANKL and inhibit osteoclasts formation - parathyroid from parathyroid gland responses to low Ca in blood and directly stimulates osteoblasts to make RANKL - calcitonin from parafollicular cells inhibit bone resorption
26
Wolffs Law
-bone that bear high mechanical weight resorp at a high rate
27
Effect of vitamin D on resorption
-aids in intestinal digestion of calcium leading to high levels of calcitonin and low levels of parathyroid thus inhibited resorption.
28
Components of bone matrix and their proportions
- 50% dry weight is calcified bone - ions such as Ca and Mg - organic matter is 90% collagen - glycoproteins ( osteonectin ) - proteoglycans
29
Surface of hydroxyapatite is hydrate So !?
-facilitates exchange between the mineral and bodily fluids
30
Periosteum structure and function
- outer fibrous dense layer of CT with collagen 1 and blood vessels - inner cellular later with mesenchymal CT and osteoblasts - supply blood vessels to bone - protective layer
31
What are sharpey fibers
-bundles of periosteum collagen which penetrate matrix and bind peri to matrix
32
Endosteal function and structure
-cover trabeculae In spongy bone -has cells ( progenitor, osteoclasts , ) And sparse Delicate network of collagen
33
Woven bone structure and where found
-irregular arrangement of cells and matrix that intertwines - found in fracture as hard callus - in developing bones
34
Woven bone characteristics
- low mineral content - low density and can’t bear much mechanical stress - high conc of osteocytes
35
Other name for woven
Primary bone | Immature bone
36
Which bone developed the quickest
Woven
37
Lamellae bone structure , characteristics , where found and synonyms
-parallel layer of thin sheets of collagen and matrix - heavily calcified - regularly spaced cells - found in all adult bones - mature bone - secondary bone
38
Types of lamellae, description, where found and function
1 interstitial bone - parallel groups of lamellae in between osteons. Made of leftover osteons from respiration 2 circumferential lamellae - external and internal found beneath periosteum and cancellous bone. Strengthens Cortical bone with osteons 3 concentric lamellae - parallel sheats of lamellae forming concentric circles and protecting Haversian canals
39
What is an osteon
-cylindrical tube parallel to long axis of diaphysis with concentric lamellae each and a Haversian canal in the middle
40
What is Haversian canal
-narrow tube between concentric lamellae with blood vessels and nerves
41
What is in between lamellae
-lacunae
42
Cement line
-outer boundary layer of a osteon
43
How are osteons formed
-by laying of matrix around pre existing blood vessels
44
Volkmanns canal structure and use
-transverse canals that connect Haversian canals together and to blood vessels of the periosteum
45
What is replaced in cortical bone during remodeling
-osteon
46
Describe bone remodeling
- osteoclasts tunnel a core through bone resorbing existing bone - tunnel invaded by capillaries and progenitor which diff into osteoblasts secrete osteoid in a cyclic manner which then calcifies forming concentric lamellae
47
What happens to trapped osteoblasts during resorption
-diff into osteocytes
48
Cancellous bone description, structure and function
- found in the middle of bone - has spicules known as trabeculae in which intertwine and are covered by endosteal - filled with bone marrow where blood is made - 20% of bone - less dense - spongy consistency
49
Cortical bone description, structure and function
- found at the peripheral of bones - underneath periosteum - 80% mass of bone - has osteons and parallel lamellae

Anatomy (15 decks)

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