lecture 3

Question 1

osteoblast

Answer 1

• osteoid (90% collagen type l)
• mineralization of osteoid
  
  • bone matrix ~ 50% of dry weight of bone, mostly calcium hydroxyapatite
• originate from mesenchymal cells

Question 2

osteocytes

Answer 2

• can’t divide
• communicate via gap junctions

Question 3

osteoclasts

Answer 3

• bone resorptions
• howship’s lacuna (resorption bay)
• ruffle border where carbonic anhydrase ll convert H+ matrix metalloproteases (enzymes degrading osteoids)
• originates from bone marrow by fusion of multiple monocytes

Question 4

intramembranous ossification

Answer 4

• osteoblasts differentiate directly from mesenchymal cells
• process used in the formation of flat bones

Question 5

first bone to ossify starting at 5th week of gestation

Answer 5

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