Endocrine: Bone Biochemistry and Histology Flashcards
Lines between Haversian Systems?
Cement Lines
Outside shaft of bone?
Cortical Bone
Support of bone?
Trabeculate bone
Two types of bone?
Cortical and Trabeculate
What part of haversian system contains blood vessel?
Central canal
What is the organic component of bone?
Type I collagen
What is the inorganic component of bone?
Hydroxyapatite
What is the embryological source of pre-osteoblasts?
Mesenchyma
What controls osteoblast differentiation?
BMP (TGFB superfamily)
What is expressed on osteoblasts?
PTH receptor and RANKL
What connects osteocytes?
Long cellular processes in canaliculi
What does osteoclast express?
RANK-R, acid
What stimulates pre-osteoblasts to express RANK-L?
PTH
What promotes osteoblast and osteoclast differentiation?
Vit D3
What induces apoptosis of osteoblasts?
Cortisol
What does calcitonin do to osteoclasts?
Inhibit
What increases bone resorption?
PTH
GC’s
T4/T3
Vit D (high levels)
What decreases bone resorption?
Calcitonin
Gonadal steroids
What increases bone formation?
Growth hormone
Vit métabolites
Gonadal steroids
What decreases bone formation?
GC’s
What happens to bone plate if osteoclasts cannot be stimulated by RANKL?
Thick and malformed
What type of collagen in cartilage?
Type II with aggrecan
When does SOST stop being expressed by osteocytes?
Fracture
Increased differentiation to osteoblasts
What is osteoporosis mostly caused by?
Decrease in estrogen, no inhibition of osteoclast activity
