Bone Development and CT Flashcards
What are the primary functions of bone tissue?
- Structure
- Locomotion
- Protection
- Calcium homeostasis
- Hematopoietic
What is the name for the shaft of a long bone?
Diaphysis
What is physis?
A growth plate
What is the name for the secondary ossification center on the non-weight bearing part of a long bone?
Apophysis
What are some examples of apophyses?
Trochanters, tuberosities, etc.
Where is the metaphysis of a long bone?
Next to the most metabolically active part of the bone, between diaphysis and epiphysis
What is the name of the expanded end of a long bone?
Epiphysis
Where is cortical bone found?
The outer shell of the bone
What is trabecular bone?
Thin bone/cancellous bone
What is the name of the less dense center of a long bone?
Medullary cavity
Where does bone pain come from? Why?
Pain comes from periosteum because it is innervated
When a physis fuses, what is left behind on the bone?
Physeal scar
What percentage of bone composition is made up of cells?
About 10%
What are four cells found in bone?
- Osteoprogenitor cells
- Osteoblasts
- Osteoclasts
- Osteocytes
What percentage of bone is organic?
About 30%
What is the primary organic component in bone tissue?
Type I collagen (about 88%)
What is the function of type I collagen in bone?
Resists tensile forces
Osteocalcin is a byproduct of…
osteoblasts
What is the function of osteopontin and sialoprotein?
Anchor cells to matrix, work to adhere things
What are the organic components of bone?
- Type I collagen
- Osteocalcin
- Osteopontin and sialoprotein
What is the function of the organic components of bone?
- Contribute to tensile strength
- Make bone more elastically and/or plastically responsive to stress
What constitutes the inorganic component of bone tissue?
- Hydroxyapatite: Ca10(PO4)6(OH)2
- Carbonate, citrate, flouride, chloride, sodium, magnesium, potassium, and strontium
What is the function of the inorganic components of bone?
- Contributes to rigidity of bone tissue
- Lends compressive strength to bone tissue
What do osteoprogenitor cells develop into?
Osteocytes or osteoblasts
Where are osteoprogenitor cells found?
Bone marrow and periosteum
What is produced by osteoblasts?
- Produces and mineralizes bone tissue
- Alkaline phosphatase and osteocalcin
- Several growth factors
What growth factors are produced by osteoblasts?
- IL-1
- FGF
- IGF-1
- IGF-2
(and others)
What is the function of osteoblasts?
Controls the differentiation and maturation of osteoclasts (production of RANKL)
What are osteoclasts?
Multi-nucleated cells in the monocyte/macrophage cell family
What is the function of osteoclasts?
Bone resorption using lysosomes and hydrolytic enzymes
What substances increase osteoclastogenesis?
Rank and RankL
What is the ratio of organic to inorganic bone components in children?
1:1
What is the ratio of organic to inorganic bone components in adults?
1:4
What is the ratio of organic to inorganic bone components in elderly?
1:7
How do changes in organic to inorganic components affect the properties of bone?
Decreased elasticity over time
A greater relative organic component produces…
increased elasticity and plasticity in response to stress
Where is the para-physiological space in the stress/strain curve?
Elastic region
Where does permanent deformity occur in the stress/strain curve?
Plastic region (after yield point)
When does failure/fracture occur in the stress/strain curve?
After the plastic region (ultimate yield point)
Which type of bone is most responsible for preventing fractures?
Trabecular/spongy bone
How does cortical/compact bone present in a stress/strain curve?
High stress with little strain percentage
Does bone have more tensile or compressive strength?
More compressive strength than tensile
Unmineralized bone is called…
osteiod
Compact and spongy bone are both ___ bone
lamellar (layered)
What are three types of compact bone?
- Circumferential bone
- Concentric lamellar bone
- Interstitial lamellar bone
What is the histology of woven bone?
- Irregular arrangement of type I collagen fibers
- Many osteocytes of different size and shape
What is the nature of woven bone?
- Deposits rapidly
- Low tensile strength
- Response to stress in adults
A tissue histologically presents with an irregular arrangement of type I collagen fibers among many osteocytes of different size and shape
What type of bone is this?
Woven bone
What gives rise to bone?
Mesenchymal condensation
In what two ways does mesenchymal condensation give rise to bone?
- Intramembranous ossification
- Endochondral ossification