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49 Cards in this Set

  • Front
  • Back
What distinguishes bone from other connective tissues
contains a mineralized matrix: Hydroxyapetite crystals (ca and phosphate)
What tyes of cells are found in bone: and function
Osteoprogenitor: stem cells

Osteoblasts: synthesize organic components of bone (type I col, proteoglycans, glycoproteins)

Osteoclasts: reabsorb bone

Osteocytes: mature cells
What are caniculi and what function do they serve
tunnels that connect adj lacunae. Allow exchange of metablites b/w cells which could not diffuse through calcified matrix:
Exchange is dependent on caniculi
1. What lines the outer surface of bones, and cavities.
2. What type of tissue is this
periosteum (2layers)
Endosteum (1layer)

Dense fibrous connective tissue
What are two major biological funx of bone
hematopoeisis and Calcium homeostacis
Where are osteoproginitor cells located
innermost periosteal layer
endosteal lining of haversions and volkmann's canals.
During remodeling on bone surface
Where are osteoproginatir cells derived?

2. What can they become if stimulated
mesenchymal cells

2. osteoblast adn possibley osteoclasts
1. Do osteoblast play a role in calcification?

2. How does the osteoblast change in relation to activity
1. yes

2. Active: cuboidal to columnar, basophilic cytoplasm and high ALKALINE PHOSPHATASE ACTIVITY. Extensive rER, prominent Golgi and polarizatio toward bone.
Less active: flatten cells
Where would you find alkaline phosphatase
in active osteoblasts and matrix vessicles, chondrocytes in zone of hypertophy
What is the osteoid?

What is it rich in
newly synthesized, not yet calcified matrix near the osteoblasts. organic component

2. GAGs
What are osteocytes?

Whats special about their cell processes?

How are organelles compared to Osteoblasts?

What is major function
1. Osteoblast surrounded w/in matrix.

2. contact via gap junx

3. reduced (golgi, rER)

4. Maintain bone matrix
1. What are osteoclasts?

2. Where are they located?

3. Where are they derived?

4. What is the role of ruffled border, and what about osteoclast in osteoporoses
1. large MULTINUCLEATED cells
2. resorption pits (howships)
3. Monocytes
4. + resorption area & allows action of enxymes
5. Lack ruffled border
What is the enzyme used by osteoclasts to breakdown (reabsorb) bone.

2. What affect does Calcitonin have, PTH
1. acid phosphatase, collagenase, proteolytic enz

2. Inhibits resorption by inducing cytoplasmic quiescence and the dissapearence of ruffled border.
3. PTH stimulates resorption by acting indirectly on osteoclasts.
What are the 2 effects of PTH
Stimulates resorption (indirectly)

2. decrease production of alkaline phophatase in osteoblast (stop building)
1. What are the 2 major components of bone matrix.
2. Majority of matrix (75%) is what?
3. What are the most abundant minerals in bone and what doe they form
1. inorganic salts, organic matrix
2. Inorganic salt
3. Ca and P = hydroxyapetite crystals
What is the organic matrix of bone
95% type I collagen, GS = GAGs, glycoproteins (bind Ca, and promote calcification)
What are the 2 layers of periosteum?

Which layer are fibrocytes found in
fibrous (outer), Cellular (inner). Cell = ostegenic layer.

2. fibrocytes = outer layer
How many laers: periosteum, endosteum.

Why is preservation of endosteum important during surgery
1. 2, 1

2. because all major bone activity occurs on bone surface.
Compare and contrast bone growth and cartilage growth
bone = only appostiional

cart = app or intersitially
1. Type of bone tissue, dense w/out cavities.

2. Bone tissue w/ interconnecting cavities
1. Compact (cortical) bone
2. Spongy (cancellous) bone
Where is spongy bone found?

Where is compact bone found?

What is red/yellow bone marrow
1. Epiphysis
2. diaphysis
3. Red = blood forming
4. Yellow = fat cells (ENG)
what is the differnce in collagen arrangement in Primary (immature) bone and Secondary (mature) bone

What about adult bone?
Imm = collagen bundles random
Mature= organized into bone lamellae

Adult = lamellated
1. What type of bone tissue is first to appear, what replaces it
1. immature
2. mature
What are the characteristics of Immature bone
1. irregular array of collagen
2. Reduced mineral content
3. more Osteocytes
How do the haversion canals communicate w/ the marrow cavity, periosteum and each other
1. By Volkmann's canals (pass through lamellae.
What happens to haversion canals during growth
1. Continuously destroyed and rebuilt
Would spicules or trabecule of bone contain Haversions canals
No, they receive nutrition by diffusion, so don't need HCs
1. Histiogenisis of bone:

2. What tissue appears first in both proceses
1. INtramebranous, ENdochondral ossfication

2. Primary bone tissue (temporary)
Where does intramembranous ossification take place?

What is the starting point?

What bones are involved in Intra
1. w/in well vascularized c.t (mesenchymal tissue)

2. Primary ossificatio center

3. Flat (occipital F,P; temoral, mandible, maxillae)
1. Type of bone tissue, dense w/out cavities.

2. Bone tissue w/ interconnecting cavities
1. Compact (cortical) bone
2. Spongy (cancellous) bone
Where is spongy bone found?

Where is compact bone found?

What is red/yellow bone marrow
1. Epiphysis
2. diaphysis
3. Red = blood forming
4. Yellow = fat cells (ENG)
what is the differnce in collagen arrangement in Primary (immature) bone and Secondary (mature) bone

What about adult bone?
Imm = collagen bundles random
Mature= organized into bone lamellae

Adult = lamellated
1. What type of bone tissue is first to appear, what replaces it
1. immature
2. mature
What are the characteristics of Immature bone
1. irregular array of collagen
2. Reduced mineral content
3. more Osteocytes
How do the haversion canals communicate w/ the marrow cavity, periosteum and each other
1. By Volkmann's canals (pass through lamellae.
What happens to haversion canals during growth
1. Continuously destroyed and rebuilt
Would spicules or trabecule of bone contain Haversions canals
No, they receive nutrition by diffusion, so don't need HCs
1. Histiogenisis of bone:

2. What tissue appears first in both proceses
1. INtramebranous, ENdochondral ossfication

2. Primary bone tissue (temporary)
Where does intramembranous ossification take place?

What is the starting point?

What bones are involved in Intra
1. w/in well vascularized c.t (mesenchymal tissue)

2. Primary ossificatio center

3. Flat (occipital F,P; temoral, mandible, maxillae)
at the primary ossification center (starting point Intram) what happens w/ cells
Groups of cells differentiate into OSTEOBLASTS, the osteoblasts become ENCAPSULATED, FORMING OSTEOCYTES
What happens to the c.t that does not undergo ossification (Intamem)
1. They become endosteum, periosteum
1. Where does Endochondral ossification take place?
2. What bones are involved
1. W/i hyaline cartilage
2. short and long bones
what are the 2 stages of endochondral ossification
1. Formation of calcified cart (hypertophy of Chondrocytes, and deposition of Ca in matrix
2. capillaries grow into perichondrium, Progeinator cells become osteoblasts that start to lay down BONE COLLAR.
1. What is the periosteal or osteogenic bud?

2. What will the bud develop, where
1. Site where periosteal vessels and progenator cells grow in.

2. Primary ossification center, (diaphysis)
In H&E sections calcified cartilage is ______, In contrast to _______ of bone tissue
1. blue
2. reddish pink
4 stages of endochondral formation
1. hypertrophy
2. Mineralization
3. Chondrocyte death
4. Osteoid on Cartilage
1. Where are primary ossificatio centers located?

2. Where are secondary oss loacated
3. Secondary centers are formed
4. How does secondary growth differ from primary
1. diaphysis
2. epiphysis
3. Postnatally
4. 2 = radial, 1 = longitudinal
1. What are the 5 zones of epiphyseal cartilage
1. Reserve cartilage
2. proliferative
3. hypertrophy
4. calcified cart
5. provisional ossification and resorption
state the components and funx
1. Zone of reserve
1.moderate-sized chondrocytes, anchors Epi plate to bone of epiphysis
2. young chondrocytes dividing rapidly, replaces dead chondrocytes
3. Large chondrocytes (swollen by glycogen) help expand epi plate and leads to formatio of next zone via alkaline phophatase.
4. Hyalin matrix calcified
5. prmary trabeculae appear