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Printable Handouts
Navigable Slide Index
- Introduction
- Tooth eruption: developing jaw
- Tooth eruption: remodeling of jaw bone
- Osteoclastic bone resorption
- Adult human bone: few osteoclasts present
- Periosteal remodelling: phalanx
- Osteoclast in resorption cavity
- Normal bone architecture
- Osteoporotic bone architecture
- Bone element eroded by osteoclasts
- Bone element perforated by osteoclast action
- Formation and activation of osteoclasts
- Rat osteoclast: motility movie
- How do osteoclasts resorb bone?
- Osteoclast regulation: Ca2+ regulating hormones
- Rat osteoclast: inhibition of motility by calcitonin
- Osteoclast regulation: systemic hormones
- Osteoclast regulation: paracrine factors
- Osteoclast formation requires M-CSF & RANKL
- RANKL: essential for osteoclast function
- OPG prevents RANKL binding to RANK
- RANK Ligand / OPG ratio is critical
- Osteocytes: potential regulators of osteoclasts
- Osteoclast regulation: further extracellular factors
- Osteoclast regulation: intracellular pathways
- Extracellular pH & osteoclasts
- Osteoclast activation: acidification required
- Acid activation of osteoclasts: Human vs. Rat
- Acid required for osteoclast stimulation by PTH
- Acid required for stimulation by RANK ligand
- Continuous resorption by activated osteoclasts
- Calvarial bone (control)
- Resorption of bone stimulated by acidosis (pH 7.0)
- Stimulation of Ca2+ release by HCO3- acidosis
- pH also controls osteoclast formation
- Low pH halts osteoclast fusion
- Osteoclasts require a mineralised substrate
- Control of bone cell function by extracellular pH
- Blood supply & hypoxia
- Bone is highly vascular
- Endochondral ossification
- Hypoxia and bone
- Normal bone can be hypoxic
- How cells sense oxygen
- Osteoclast formation from blood cells
- Hypoxia & osteoclast formation: microscopy
- Hypoxia & osteoclast formation: quantification
- Hypoxia causes maximal Ca2+ release
- Control of bone cell function by oxygen tension
- Detailed formation and activation of osteoclasts
- Osteoclasts: summary
- Hypothermia stimulates osteoclast formation
- Blood flow, oxygen tension and bone cell function
- Hypoxia & acidosis
- Tumour metastases: the ‘vicious cycle’ model
- Thank you
Topics Covered
- Formation and activation of osteoclasts
- Osteoporotic bone architecture
- Osteoclastic bone resorption
- Osteoclast motility and its inhibition
- Osteoclast regulation (hormones & other important factors)
- The role of low pH (acidosis) in bone loss
- Hypoxia & control of bone cell function by oxygen tension
Talk Citation
Arnett, T. (2015, January 19). Pathways regulating bone resorption [Video file]. In The Biomedical & Life Sciences Collection, Henry Stewart Talks. Retrieved December 14, 2024, from https://doi.org/10.69645/ILWO1949.Export Citation (RIS)
Publication History
Financial Disclosures
- Prof. Tim Arnett has not informed HSTalks of any commercial/financial relationship that it is appropriate to disclose.
Other Talks in the Series: Bone in Health and Disease
Transcript
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0:00
Osteoclasts are among the most
remarkable cells in the body.
In this lecture, in
addition to outlining
their key regulatory pathways,
I want to address some aspects
of osteoclast biology that
might be less well known,
with a special focus on the roles of
the fundamental parameters, oxygen
tension, and pH.
0:22
If you want to see osteoclasts
in action, a good place to start
is actually to look at erupting
teeth in the developing jaw.
In this image, you can see
adult teeth embedded in the jaw,
and milk teeth protruding
from the gum above.
The developing adult teeth that
are embedded in the jawbone
have to make their way
through the jawbone
in order to erupt and
serve their function.
0:48
This image shows, in higher power,
the developing, erupting adult
tooth surrounded by
the concave bone.
Lining the bone, you can
see a number of large cells
is the osteoclast.
And these are in the process of
eroding away the bone of the jaw,
the alveolar bone, in order
to make way for the tooth.
1:11
At higher power, we see the row of
osteoclasts on the bone's surface.
And we see that each
osteoclast is embedded
in a concavity in the bone.
This is the process
of bone resorption.
In juveniles, such as the
specimen we're seeing here,
osteoclasts may be quite frequent.
1:34
However, in adult bone, osteoclasts
occur far less commonly.
But, for example, if we look at
this section of a human finger bone,
there's only a very small
area, highlighted here,
in which osteoclast
activity is evident.