Lecture 8 - Bones And Joints Flashcards
What joint is an example of a joint capable of a range of angular movements due to ball and socket formation?
Shoulder
Movement requires muscles that are usually * around the joint, with the joints being the ** for muscle *
antagonistic; focal point; attachment
Define bursa
Fluid filled sac with important role in decreasing friction and protecting surrounded tissues
What does bone remodelling allow?
Allows maintenance (damage response) Allows changes in response to change in stress and strain
What is bone turnover rate?
10% per year
4% cortical (compact) bone
28% trabecular (spongy) bone
How are osteocytes, osteoclasts and osteoblasts involved in the remodelling process?
Osteocytes - bone formation, mineralisation, cell control, transduction of information about stress and strain
Osteoclasts - resorption
Osteoblasts - bone formation
Remodelling shows * and * variation, dependent on *
circadian; seasonal; diet
What is calcified bone a source of? Why?
What is it used for?
Skeletal system can be harmed if **
It’s a source of calcium for the rest of the body, because metabolic needs are greater than skeletal needs
Used in cardiac contractility and nerve transmission
Nutrient deficient
How is extracellular calcium (1-2mM) regulated?
Parathyroid glands release the parathyroid hormone to increase blood calcium
C cells of the thyroid release calcitonin to decrease blood calcium
What are the mechanisms of calcium regulation?
Mobilisation (calcium from bone)
Calcium resorption from kidneys
Calcium absorption from intestines
What can happen if bone resorption and formation isn’t balanced?
Gigantism - hypersecretion of growth hormone
Dwarfism - no collagen in bone due to mutation
Acromegaly- adult version of gigantism
What does bone mineral density indicate?
How is it measured?
What is it useful for?
Indicates bone strength
Measured by dual energy XRay absorptiometry (DXA) scan which determines what proportion of X Ray energy has been absorbed
Assessing the risk of fracture and osteoporosis (where the amount of bone decreases, structural integrity of trabecular bone is decreased and cortical bone thickness and integrity is reduced
What two things can cause decrease in bone mass?
What are the treatments? Elaborate on one
Age and menopause
Exercise; calcium and vitamin D supplements; hormone replacement therapy and oral bisphosphonates (accumulate in bone through calcium binding and ingested by osteoclasts which then die through apoptosis)
Athletes have a higher bone **
Exercise slows ** loss of *
High impact is * effective and is related to * of *
However you need to extend exercise beyond **, as * responses * after a few loading cycles
- periods between loading cycles can * response
Mineral density
Age related; BMD
More; magnitude; strain
Habitual levels; adaptive; decrease
Rest; increase
What is the process of mechanotransduction? (linking mechanical force to cell response and remodel)
1) exercise (dynamic/high impact/resistance)
2) stress/mechanical load on bone
3) altered flue flow in lacuna - canalicular fluid
4) osteocytes detect shear stress and hydrostatic pressure waves (sensors are integrins and others)
5) there is cell-cell connectivity
6) hormonal/biochemical messengers
7) bone cell recruitment of osteoblasts and osteoclasts
8) protein secretion, mineralisation, autocrine remodel control
