Bone Flashcards
Pressure applied to bone induces what type of remodeling?
Resorption
Tension applied to bone induces what type of remodeling?
Deposition
What are the epiphyses?
Ends of bones
What are the metaphyses?
Angulation between epiphysis and diaphysis
What are the diaphyses?
Shaft of bone
What is the periosteum?
External connective tissue capsule of bone
What layers are present in active (growing) periosteum?
- Outer fibrous layer2. Inner cellular layer
What layers are present in inactive (mature) periosteum?
Only well-developed outer fibrous layer
How is the fibrous layer of periosteum anchored to the bone?
Sharpey’s fibers
What are Sharpey’s fibers?
Bundles of collagenous fibers; anchor fibrous periosteum to bone
In the inner cellular layer of periosteum, what cells are present in a growing bone?
Osteoprogenitor cells
In the inner cellular layer of periosteum, what cells are present in a non-growing bone?
Periosteal cells
Does periosteum cover the bone at articular surfaces?
No
Does periosteum cover the bone where tendons attach?
No
What is the endosteum?
Internal connective tissue capsule of bone
What makes up the endosteum?
Thin layer with single row of osteoprogenitor cells
Endosteum lines what compartments within bone?
- Bone marrow cavity2. Haversian and Volkman canals3. Spicules and trabeculae
What gives bones their hardness?
Inorganic minerals
What are the inorganic components of bone?
- Hydroxyapatite crystals (calcium phosphate)2. Bicarbonate, citrate, magnesium, sodium, potassium
What makes up the organic component of bone?
- Fibers2. Ground substance
What is the function of the organic component of bone?
Prevents brittleness
What is the main type of collagen in the organic component of bone?
Type I
What are the components of the ground substance in bone?
- Proteoglycans2. Multiadhesive glycoproteins3. Bone-specific, Vitamin K dependent proteins4. Growth factors and cytokines
What is the function of proteoglycan side chains in the ground substance of bone?
Binding growth factors
What binds growth factors in the ground substance of bone?
Proteoglycan side chains
What are the multiadhesive glycoproteins in the ground substance of bone?
- Osteonectin2. Sialoproteins
What is the function of osteonectin?
Serves as glue between collagen and hydroxyapatite crystals
What serves as glue between collagen and hydroxyapatite crystals?
Osteonectin
What are the sialoproteins?
- Osteopontin2. Sialoproteins I and II
What is the function of osteopontin?
Binds cells to bone matrix
What binds cells to bone matrix?
Osteopontin
What are the functions of sialoproteins I and II?
- Bind cells to bone matrix2. Begins calcium phosphate formation during mineralization
What is an example of a bone-specific, Vitamin K dependent protein?
Osteocalcin
What is the function of osteocalcin?
- Traps calcium from blood2. Stimulates osteoclasts to remodel bone
What traps calcium from blood and stimulates osteoclasts to remodel bone?
Osteocalcin
What are the functions of bone morphogenic proteins (BMPs)?
- Induce mesenchymal cells to differentiate into osteoblasts2. Used following surgery to stimulate bone formation
What induces mesenchymal cells to differentiate into osteoblasts?
BMPs
What is used following surgery to stimulate bone formation?
BMPs
What is the term for osteoprogenitor cells located in the inner layer of the mature periosteum?
Periosteal cells
What is the term for osteoprogenitor cells located in the endosteum?
Endosteal cells
Can osteoprogenitor cells undergo mitosis?
Yes
In low oxygen tension, what do osteoprogenitor cells differentiate into?
Chondrogenic cells
Are osteoprogenitor cells active during bone growth?
Yes
What is the cell shape for osteoblasts?
Cuboidal - columnar
Are osteoblasts basophilic or acidophilic?
Basophilic
What is osteoid?
Newly formed non-mineralized bone (“pre-bone”)
What is the composition of osteoid?
- Type I collagen2. BMPs
Osteoblasts have high concentrations of what enzyme?
Alkaline phosphatase
During bone deposition, is there an increase or decrease in serum alkaline phosphatase levels?
Increase
How to osteoblasts communicate with each other?
Gap junctions
What are the functions of bone lining cells?
- Nutritional support of osteocytes2. Uptake and release of calcium and phosphate by bone tissue
What is the periosteocytic space?
Space between osteocyte cell membrane and the lacuna and canaliculi
Are osteoclasts basophilic or acidophilic?
Acidophilic
What causes acidophilic nature of osteoclasts?
Acid-containing lysosomes
Osteoclasts are derived from ________________
Mononuclear hematopoietic progenitor cells (CFU-GM)
Where are osteoclasts found?
Howship’s lacuna
What is Howship’s lacuna?
Enzymatically-etched shallow depression where osteoclasts are found
An osteoclast actively breaking down bone has what morphological characteristics?
- Ruffled border2. Clear zone 3. Basolateral region
What is the function of the clear zone in an active osteoclast?
Sealing zone to isolate corrosive materials
The acidic environment of osteoclasts breaks down what component of bone?
Inorganic component
What enzyme types break down the organic component of bone?
- Lysosomal hydrolases2. Metalloproteinases (collagenase, gelatinase)
What happens to osteoclasts when they are done with bone resorption?
Apoptosis
The diploe found between inner and outer tables of the skull cap is characterized as what type of bone?
Cancellous bone
What is the main morphological characteristic of compact bone?
Haversian systems (osteons)
What is the main morphological characteristic of cancellous bone?
Bone lamellae (layers)
Is primary bone temporary or permanent?
Temporary
What is the morphology of primary bone?
Irregular / interlacing bundles of collagen (nonlamellar)
What is the morphology of secondary bone?
Parallel or concentric bone lamellae
What is the Haversian canal?
Vascular space that encloses a neurovascular bundle, but NOT lymphatic vessels
What is the only component of bone that has lymphatic vessels?
Periosteum
What are Volkmann canals?
Perforating canals; obliquely oriented; connect osteons that are next to each other
Do Volkmann canals have concentric lamellae?
No
In what direction to osteons form?
Outside-in
Where are inner circumferential lamellae?
Around the marrow cavity
What is anklyosis?
Condition in which two articulating bones fuse, obliterating the joint so there is no movement
What is the cause of ankylosis?
Trauma to hyaline cartilage which causes it to become calcified and replaced by bone
What is rheumatoid arthritis?
Autoimmune disease that attacks synovial joints, damaging articular cartilages
What is gouty arthritis?
Caused by accumulation of uric acid crystals
Trauma to hyaline cartilage which causes it to become calcified and replaced by bone
Ankylosis
Autoimmune disease that attacks synovial joints, damaging articular cartilages
Rheumatoid arthritis
Caused by accumulation of uric acid crystals
Gouty arthritis
What is rickets?
Disorder resulting from calcium deficiency during development, or from inadequate vitamin D which is necessary for calcium absorption from the GI tract
What is osteoporosis?
Condition characterized by reduction in bone mass in both components of bone matrix