bs2 mod 3 Flashcards
What forms appendicular skeleton
Lateral plate mesoderm
Describe osteogenesis
Making of bone. Start out with BMP stim of Runx (then TRAF6) leading to progenitor to diff into osteoprotenitor. Then osterix leads it to differentiate into osteoblast. The ones that get trapped become osteocytes. The ones that don’t differentiation become periosteum and endosteum
periosteum layers
Fibrogenic outer layer with BP and sharpens fibres (extension of tissue into bone)
Osteogenic inner
bone formation
collagen deposition (steel bars) then ground substance made then seeding where ground substance saturated with Ca and P and precipitate out then mineralization when crystals are tethered to collagen by proteoglycans that give bone strength
Describe osteoclastogenesis
MCSF binds to monocyte to make macrophage.
Start out with MCSF stim on osteoblast?? RANKL made by osteoblast, t cells and MSCm chondrocytes too. Binds to RANK on monocyte to turn it into osteoclast
type 11 collagen
Type 11 is minor that attaches to type 2
Describe chondrogenesis
mesenchyme prolif and condense to prechondrocyte (signal by TGFb and WNT) then mature and hypertrophy to make room for vascular invasion
where do you find hyaline cart
respiratory passage, larynx, nose, articular surface of bones, ventral ends of ribs
Transient: skeleton model, epiphyseal growth plate
Sox9 mutation:
campomelic dysplasia
controls type 2 coll and aggrecan so autosomal dominant and bad. Bowing and angulation of long bones (sock shape) and Craniofacial abnormality
when does posterior fontanelle close
3 mos
intramem ossification
Mac to prolif and condense then diff to osteoblast via BMA stim of RUNx2. Vascular invasion via VEGF then form ossification centre
*priosteum is fiber layer where vascular MSC condense
starts in suture lines and periosteum from progenitor cells
endochondral ossification
Msc prolif then chondrocytes make type 2 collagen, then FGF and RUNX2 make hypertrophy then VEGF
- MSC to prechondrocyte is TGFb and want
- Prechondrocyte to chondrocyte is sox9 (disorder is campomelic dysplasia)
- Starts from growth plates and end plates from chondrocytes
Vascular growth plate makes what
type 1 coll
process of bone width growth
Width bone growth: periostea ridge pinches off to form endosteum that grows out by secreting matrix and forming lamella by making type 1 fibres
appositional is where bone resorbed in thick area to add to thin area
What does thyroid hormone do to bone growth
DELAYED
activation of bone remodelling
activation (recruit osteoclast) to resorption then reversal (osteoclasts die and osteoblast recruited) then formation/mineralization
osteocyte control
Cites make OPG and NO to stop osteoclast. Stim osteoclast by making MCSF and RANKL
runx mutation
Cleidocranial dystosis
- messed up collarbone, open fontanelle
- teeth
osterix mutation
osteogenesis imperfecta
b catenin does what
Regulates osteoclastogenesis since controls osteoprotegin and RANKL on osteoblast
TGFb signal
tgfb is stored in ECM. Binding turns on canonical and non canonical. Stops osteoblast progenitor and makes osteocyte instead
how does indian hedgehog work
Allows osteoblast prolif by increasing Runx2 and sox. Inhibited by PTCH
what does FGF do
regulate both endochondral and intramem ossification by control osteoblast prof, diff and APOPTOSIS
turns on Runx
What happens in RANKL mutation?
Mutation causes pages disease: bone bending, tooth loss. Too much osteoclast
OPG mutation is juvenile pages where suture problem effects osteoblast diff (OBGYN = baby)
What are proinflammatory factors vs inflammatory and what do they do
ROS in age, proinflam induce OC Diff (TNFa, Il1 and Il6) and antiinflam does inhibit of OC (il 4, 10, IFN a and IFN b).
ca release from ER
IP3 then ca out then protein kinase c then calmodulin
Which organs/cells have PTH receptors
Receptor is PTH1R is mostly on kidney and bone!! Also in growth plate chondrocytes!
which organs have serum ca sensing receptor
Serum Ca sensing receptor is GPCR. ON parathyroid and c cells of thyroid. Also in kidney, chondrocytes and osteoblasts
catabolic and anabolic functions of PTH
catabolic PTH: high PTH means promote osteolysis using higher RANKL
Anabolic: low PTH is 4 stage: promotes RUNX2 and osx to diff to osteoblast. Sclerotin is the wet inhibitor so decrease it to promote bone formation
Describe calcitonin structure
32 AA peptide. No diff if its taken out on ca homeostasis!
Describe the PO4 levels in the body
Po4 normal level is 3.0 to 4.5 mg/dl. 87% is diffusible with 35% completed to diff ions and 52% ionized.
13% is non diffusible protein bound. 85-90% is in bone.