Bone Metabolism Flashcards
Which cell makes type 1 collagen?
osteoclasts
osteoblasts
osteocyte
osteoprogenitor
Which cell makes type 1 collagen?
osteoclasts
osteoblasts
osteocyte
osteoprogenitor
Which molecule activates precursor osteoclast into activated osteoclast? [1]
RANKL
Which locations in bone tissue do you find osteoprogenitor cells? [2]
- periosteum
- endosteum
review bone histology
At birth, all bone marrow is [red / yellow]
As you age, bone marrow turns [red / yellow]
At birth, all bone marrow is red
As you age, bone marrow turns yellow
Name two places that may find red bone in an adult [2]
spongy / trabeculae bones of vertebrae, ribs, sternum, cranium and epiphyses of long bones
Which structure do osteocytes sense mechanical stress via? [1]
canaliculi: If the bone is very stressed and the canaliculi break, then the osteocytes cellular processes are damaged, which leads to osteocyte death and bone remodelling ensues
Asides from osteoblasts (which then can turn into osteoclasts), which cell type can osteoprogenitor cells differentiate into? [1]
Chondrocytes
Describe the composition of bone [3]
35-40% organic
* Type 1 collagen (90% tensile strength)
* Proteoglycans (compressive strength)
* Growth factors / cytokines / osteoid
60% inorganic
* 95% Calcium hydroxyapatite (Ca10(PO4)6(OH)2)
* Approximately 5% water
Describe the structure of collagen in bone [1]
Describe how calcium hydroxyapatite is structured on bone collagen [1]. Why is this significant [1]
Collagen in a triple helix
Calcium hydroxyapatite on intermittent blocks on collagen - so not too brittle
Osteoclasts are derived from which cell type? [1]
Where does this come from in the bone? [1]
Macrophage lineage - red bone marrow
What is the difference in structure between active and inactive osteoblasts? [2]
Cuboidal osteoblasts: active
Flattened osteoblasts: inactive
Which cell type is this?
osteoblast
osteoprogrenitors
osteoclast
osteoid
osteocyte
Which cell type is this?
osteoclast
Which molecule signals healthy bone structure?
RANLK
OPG
Sclerostin
PTH
Sclerostin: high levels of sclerostin switches OFF osteoblasts
Describe the mechanism of osteocytes and the production of sclerostin when mechanical stress occurs [2]
Osteocytes sense mechanical stress of bone: death of osteocytes signals remodelling
* Healthy osteocytes produce sclerostin and switch OFF osteoblasts
* Damaged osteocytes: stops producing sclerostin and osteoblasts do not have inhibitory signal / become active