Bone Formation

Question 1

Types of Bone Formation with examples?

Answer 1

Intramembranous Ossification (w/o cartilage template)
- skull, surface of long bones

Endochondral Ossification (w/ cartilage template)
- vertebrae, length of long bones

Question 2

Steps of intramembranous ossification?

Answer 2

• mesenchyme cells aggregate
• differentiate into osteoblasts (release osteoid)
• differentiate into osteocytes
• woven bone
• shell of compact bone with trabecular bone in centre

Question 3

What is needed for bone development?

Answer 3

blood supply

Question 4

Steps of endochondral ossification?

Answer 4

• hyaline cartilage template of long bone
• perichondrium –> periosteum
• chondrocytes = hypertrophic
• cartilage matrix calcifies
• blood vessel enter dead cartilage and bring osteoprogenitors

Question 5

Centres of ossification?

Answer 5

Primary centre = bone marrow cavity of diaphysis
Secondary centres = both epiphysis

Question 6

Zones in Epiphyseal Growth Plate?

Answer 6

zone of reserved cartilage (called upon enter growth)
zone of proliferation (linear stacked)
zone of hypertrophy (larger cells)
zone of calcification (osteoid)
zone of resorption (cartilage resorb = new bone)

Question 7

4 steps of fracture repair?

Answer 7

fracture hematoma (clot)
soft callus (hyaline cartilage)
hard callus (endochondral ossification)
bone remodelling

Question 8

What is osteoporosis?

Answer 8

imbalance between osteoblasts and osteoclasts
- resorb more bone than made

Question 9

Osteon development?

Answer 9

• osteoclast dig tunnel (cutting cone)
• osetoblasts lay down behind (closing cone)