Term
Charactertistics:
Specialized connective tissue
Ability to withstand stress
One of hardest tissues in body
Functions:
skeleton
supports and protects
contains bone marrow
stores calcium
muscles attach
Components
Cells
Fibers
Ground substance
Mineral
Very little water
all these comprise what type fo specialized CT? |
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Definition
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Term
Have well-developed rER and Golgi complex
Located at surface of bone tissue
Cells lined up side by side
Are cuboidal in shape, but polarized
Nucleus on side away from matrix
Basophilic cytoplasm
what type of cell has these characteristics? |
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Definition
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Term
Osteoblast synthesize and secrete organic components of bone called?
Inorganic components? |
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Definition
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Term
Incapable of mitosis (no isogenous groups)
Maintain bone matrix, not actively synthesizing matrix
Less rER and Golgi than osteoblasts.
Osteoblasts surrounded by bone matrix
What cell has these characteristics? |
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Definition
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Term
Contain filopodial processes- extensions of the cell
Cells make contact with each other with gap junctions
Lies in a lacuna
Filopodial processes lie in extensions of the lacuna called canaliculi
What cell has these characterisitics? |
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Definition
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Term
Derived from blood monocytes- mononuclear phagocyte system
Contain many nuclei (multinucleate) (2-50)
Acidophilic cytoplasm, abundant mitochondria, well-developed Golgi complex
Responsible for bone resorption
Surface that faces bone matrix has a ruffled border- provides large surface area
Lie in an enzymatically etched depression called Howship’s lacunae
Contain proteolytic enzymes, and acids, numerous lysosomes
Respond to PTH via signal from osteoblast- increase activity
Have receptors for calcitonin- decrease activity
What cells have these characteristics? |
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Definition
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Term
Provides blood supply for nutrition of cells
Provides continuous supply of new osteoblasts
Connective tissue surrounding capsule
Has 2 Layers
Fibrous layer- outermost layer
- Collagen and fibroblasts
- Dense regular CT
Osteogenic layer- inner layer,
very cellular
- Contains osteoprogenitor cells- have ability to divide and differentiate into osteoblasts
- Contain Sharpey’s fibers (collagen fibers that penetrate bone matrix and bind periosteum to bone)
What has these characteristics? |
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Definition
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Term
Lines marrow cavity and extends into Haversian canals
Composed of reticular tissue
Contains osteoprogenitor cells
Thinner than periosteum
Lines all internal surfaces of bone
What has these characteristics? |
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Definition
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Term
| What has type-I collagen fibers, ground Substance (GAGs, proteoglycans, glycoproteins), and minerals (calcium, phosphate, hydroxyapatite crystals) |
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Definition
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Term
Provides resistance to tension
Type I collagen
Ground substance
GAGs
GP (bone sialoproteins, osteonectin, osteopontin)
PG (Chondroitin 4 & 6 sulfate, keratan sulfate)
Removal of this organic material results in structure with same shape, but very fragile and breaks easily |
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Definition
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Term
Provides resistance to compression
Provide hardness and rigidity
Calcium, Phosphate (bicarbonate, citrate, Mg, K, Na)
Hydroxyapatite crystals- along collagen fibrils
Removal of inorganic portion of bone results in structure with same shape, but becomes very flexible. |
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Definition
| Mineral Portion- inorganic (50%) |
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Term
Bone Matrix: Calcification
Proteins (osteocalcin and osteonectin) in osteoid that bind Ca++
Matrix vesicles containing alkaline phosphatase bud off from osteoblasts
Alkaline phosphatase liberates phosphate groups
Calcium and phosphate precipitate into an insoluble salt called hydroxyapatite |
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Definition
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Term
| Associates closely with collagen fibrils, this association results in hardness and resistance of bone |
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Definition
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Term
Bone Matrix: Calcium Mobilization
???
rapid mobilization- along a concentration gradient
physical transfer of ions into interstitial fluid, then to blood
???
acts on osteoblasts (have receptors)
osteoblasts secrete cytokines which stimulates osteoclasts
increased bone resorption
???
acts directly on OC (on calcitonin receptors)
inhibits resorption activities of OC
stimulates bone deposition by osteoblasts |
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Definition
Physical mechanism
Parathyroid hormone
Calcitonin |
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Term
What histological section of bone has these characterisitics?
Demineralize bone tissue in acid
Fix tissue, embed in paraffin or plastic
Section on microtome, stain
Cells are fixed and remain in tissue |
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Definition
| Demineralized bone preparations |
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Term
What histological section of bone has these characterisitics?
Cut piece of bone with a saw
Attach bone piece to slide with glue
Grind bone until only thin piece left
Stain with ink
Cells not preserved
Ink fills spaces, can see arrangement of bone tissue |
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Definition
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Term
No open spaces or trabeculae
Contains Haversian systems (osteon)
Organized into lamellae
Location
Covers spongy bone in epiphyses
Diaphysis
Flat bones of skull
Always secondary bone |
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Definition
| Compact bone- (cortical, dense or lamellar bone |
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Term
Parallel to long axis of diaphysis
Lined by endosteum
Contains blood vessels, nerves, lymphatic vessels
Lamella farthest from blood vessel forms first
What canal in compact bone has these characteristics? |
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Definition
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Term
Run perpendicular to Haversian canals
Link Haversian canals
Do not have concentric lamellae- perforate Haversian lamellae
Lined with endosteum
What canal in compact bone has these characteristics? |
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Definition
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Term
| Concentric layers (lamellae) surrounding a Haversian canal |
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Definition
| Haversian system (osteon) |
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Term
| True or False: Lamellae are layers of bone tissue. The collagen fibers are arranged in parallel fashion in each lamella, but are perpendicular to the fibers in adjacent lamellae. |
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Definition
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Term
| “Rings” of bone tissue surrounding an Haversian canal |
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Definition
| Concentric Lamellae (Haversian lamellae) |
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Term
Amorphous material surrounding each Haversian system
Consists of mineralized matrix with few collagen fibers
Helps anchor osteons
What substance has these characteristics? |
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Definition
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Term
| “Rings” of bone tissue lining the outer portion of the bone, immediately beneath the periosteum |
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Definition
| Outer circumferential lamellae |
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Term
“Rings” of bone tissue surrounding the marrow cavity
lined by endosteum |
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Definition
| Inner circumferential lamellae |
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Term
| Partial lamellae between osteons- parts of old osteons |
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Definition
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Term
| True or False: Compact bone is mostly found in diaphysis |
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Definition
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Term
Structure of bone tissue (spongy or compact)
Time of synthesis (primary or secondary)
Type of bone formation (endochondral or intramembranous)
are ways to classify??? |
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Definition
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Term
| True or False: Primary bone is the first bone synthesized and secondary bone is remodeled bone |
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Definition
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Term
The first bone to appear during formation and repair
Formed by intramembranous or endochondral bone formation
Is temporary, replaced by secondary (except in tooth sockets and near sutures of flat bones)
Collagen fibers arranged in irregular array
Smaller content of mineral- more easily penetrated by x-rays
Higher proportion of osteocytes
Immature bone, woven bone
Always Spongy Bone |
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Definition
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Term
Collagen fibers arranged in lamellae parallel to each other in spongy bone
Collagen fibers in lamellae arranged concentrically around a vascular canal in compact bone
Mature bone, more organized than primary bone
Spongy or Compact Bone |
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Definition
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Term
Remodeling compact bone
1. Osteon (usually only parts of an osteon) resorbed by osteoclasts.
2. Resorbed areas invaded by osteoblasts and new blood vessel growth.
3. A new osteon forms.
Bone continuously remodeled throughout life
Bone responds to stress on the tissue |
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Definition
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Term
Growth in girth of bone
bone marrow cavity expands
thickness of compact bone stays the same
Growth in girth- resorption of osteons and formation of new osteons
Differentiation of cells in periosteum and new osteoid deposited in outer portion of the bone.
The thickness of the bone stays the same- the inner marrow cavity expands in size.
The marrow cavity expands into the space that was occupied by bone tissue. |
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Definition
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Term
No cartilage model formed
Mesenchyme differentiates directly into osteoblasts to form bone
Bones of the head form this way (derived from neural crest-Ectoderm)
Layer of spongy bone (diploe) between compact bone
What is this process called? |
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Definition
| Intramembranous Ossification |
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Term
| True or False: Flat bone anatomy comprises of spongy bone lodged in between and outer and inner layer of compact bone |
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Definition
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Term
| True or False: Intramembranous ossification exhibits flat bone anatomy usually found in the head |
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Definition
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Term
Mesenchyme condensations formed
Mesenchyme cells differentiate to form chondroblasts
Cartilage model of each skeletal structure formed
Cartilage model has the same shape as future bone
Chondrocytes become more specialized
“Zones” of chondrocytes form the epiphyseal plate
The epiphyseal plate is responsible for the growth in length of the bones
Long bones form this way |
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Definition
| Endochondral Ossification |
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Term
| True or False: The zones of chondrocytes are responsible for growth and length. Also represents where cartilage turns to bone. |
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Definition
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Term
The hierachy of Endochondral Bone Formation:
Resting Zone --> Zone of Proliferation --> Zone of Hypertrophy --> Zone of Calcification --> Zone of Ossification |
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Definition
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Term
The first area in the bone to begin the ossification process.
near the middle of the diaphysis in long bones |
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Definition
| Primary ossification center |
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Term
Begins after primary centers.
in the epiphyses of long bones |
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Definition
| Secondary ossification centers |
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Term
| The region between a primary and secondary ossification center |
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Definition
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Term
Form the tubercles and ridges to which large muscle groups attach
only on some bones |
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Definition
| Tertiary ossification center |
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Term
Fracture Repair
1. Fracture of bone causes damage to blood vessels in perichondrium, endosteum, and Haversain systems
2. Damaged blood vessels produce localized hemorrhage
3. A blood clot forms
4. Osteoprogenitor cells in periosteum and endosteum differentiate into fibroblasts, chondroblasts, and osteoblasts
5. Macrophages enter and break down clot
6. Connective tissue fills space
7. Chondroblasts deposit cartilage
8. Callus formed- connective tissue and cartilage model
9. Callus replaced by primary bone
10. Trabeculae form in fracture area to unite bone
11. Primary bone remodeled in response to stress |
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Definition
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