Ch 6, 5 Bone development

Question 1

osteogenesis (ossification)

Answer 1

stages in bone tissue formation

1. bone formation-begins in 2nd month of development
2. postnatal bone growth-until early adulthood
3. bone remodeling and repair-lifelong

Question 2

intramembranous ossification

Answer 2

• bone develops from fibrous membrane
• forms flat bone
  1. ossification centers develop in fibrous CT membrane
  2. osteoid is secreted and calcifies
  3. woven bone and periosteum form
  4. lamellar bone replaces woven bone, red marrow develops

Question 3

endochondral ossification

Answer 3

• bone formed from hyaline cartilage model
• cartilage is broken down and replaced by bone
• forms most of the rest of the skeleton
  1. primary ossification center forms cone collar
  2. cartilage in center of diaphysis calcifies then develops cavities
  3. spongy bone begins to form in cavity
  4. diaphysis elongates, medullary cavity forms, secondary ossification centers develop at epiphyses
  5. epiphyses ossify, hyaline cartilage remains only at epiphyseal plates and articular cartilages

Question 4

interstitial growth

Answer 4

increases the length of bones

occurs at articular cartilages and epiphyseal plates

Question 5

appositional growth

Answer 5

increases thickness and remodeling of all bones by osteoblasts and osteoclasts on bone surfaces

Question 6

growth in length in long bones

Answer 6

epiphyseal plate cartilage organizes into 4 functional zones:

1. proliferation (growth)
2. hypertrophic
3. calcification
4. ossification (osteogenic)

Question 7

hormonal regulation of epiphyseal bone growth

Answer 7

• growth hormone stimulates epiphyseal plate activity
• thyroid hormone modulates activity or growth hormone
• testosterone and estrogens (at puberty)
• -promote adolescent growth spurts
• -end growth by inducing epiphyseal plate closure

Question 8

adult bone growth

Answer 8

usually no further bone growth happens except for remodelling