Bones n stuf Flashcards
Golfers / tennis elbow?
Lat / medial epicondyltitis
Attachment of EXTENSOR CARPI RADIALIS BREVIS tendon
Exercise effects on tendon?
Increased size of fibrils
Increased strength
Increased stiffness
Exercise effects on ligament
Increased small fibril number
Increased fibril number
Increased collagen content
Immobilisation effects on tendon?
Drop in PG content
Drop in strength
What does synovium do?
Secretes synovial fluid into tendon sheath which tendon slides through
What is the GAG that gives synovial fluid its lubricating quality?
Hyaluronan
Draw a sarcomere
.
Describe a muscle contraction
Calcium release from SR when action potential arrives down T tubule
Calcium binds with troponin causing conformational change that removes tropomyosin from myosin binding site; they join
Power stroke due to energy from previous ATP hydrolysis
ATP binds to ATP binding site on myosin heads, allowing disconnection of the two fibres
ATP hydrolysis occurs, which stores energy for next power stroke
Sources of ATP in muscle
Phosphocreatine dephosphorylation:
- v fast but v limited
- ADP + PC ATP + C
- CREATINE PHOSPHOTRANSFERASE
FFA oxidation:
- Produces CO2, H2O and ATP
Carbs (ox phosphorylation):
- ATP + H2O + CO2
Carbs (glycolysis; glycogen)
- due to pyruvate being formed faster than TCA can oxidise it
- lactic acid + ATP
What do bone anabolics do?
- PTH, prostanoids
Promote bone formation
- Increase bone mass but not replace lost architecture
What do anti-catabolics do?
- Estradiol, bisphosphonates
Reduce bone resorption
- Increase bone mass but not replace lost architecture
What is rate of bone loss/formation determined by?
- no. of ‘clasts versus ‘blasts
- bone balance (e.g. PTH, vitamin D, oestrogen)
Stages of bone remodelling?
Resting Injury Resorption Reversal Deposition Resting
How is cartilage calcified?
Chondrocytes respond to anoxic environment (remember bone collar) and hypertrophy and release ALP
What is ossification and how does it occur?
Ossification is mineralisation of osteoid
Osteoid is secreted by osteoblasts, then later calcium hydroxyappatite (mainly) is secreted, also by osteoblasts
What causes achondroplasia?
Mutation in bFGF receptor
- decreased chondrocyte proliferation
- early growth plate closure
- decreased longitudinal bone growth
WEEMAN!
Osgood-Schlatter disease?
Inflammation of patellar tendon due to overuse
Salter Harris fracture
Fracture involving growth plate - 15% of childrens fractures
Lamellar bone structure?
Calcium crystals INSIDE fibrils; comes after woven bone
Woven bone structure?
Calcium crystals OUTSIDE fibrils; coems before lamella bone, not v strong
What is rickets, or osteomalacia?
Dietary vitamin D deficiency: rickets = children, OM = adults
Causes softening and distortion of bone; typically causes varus
Due to failure of osteoid to calcify
Osteoclasts work by…
Secreting LYSOZOMAL enzymes; form HOWSHIPS LACUNAE
Always found on surface of bone, nowhere else
What things are particularly involved in regulation of bone deposition /mineralisation?
BMPs
Osteopontin*
Osteonectin*
Osteocalcin*
*Glycoproteins
What do osteoblasts do?
- Osteoid secretion
- Osteoid clacification (ca-hydroxyapatite)
Paget’s disease
LARGE AND MISSHAPEN BONES Bone pain Fractures Deafness Bone thickening Craniofacial compllications Neuro problems Visual problems Deformity
- Caused by excessive breakdown of bone (o’clast activity) followed by disorganised bone growth
Differences between young and old cartilage?
Young:
- Cellular
- No morphological zones
- No tidemark
- Little ECM
Old = opposite
Why does cartilage degrade without use?
It has no direct blood supply for nutrients and the tidemark cuts off its direct diffusion, therefore it requires the synovial fluid to deliver nutrients from the bone vasculature, but for this to occur the cartilage needs to be used (under load) to squeeze the fluid around
Collagenases
Degrade triple helix collagens
Gelatinases
Degrade degraded collagens
Stromelysins
Degrade non-collagen matrix proteins; not aggrecan
Aggrecanases 1&2
ADAMTS 4&5
- cleave aggrecan at IGD between G1 and G2, allowing release of aggrecan from the aggregate
- major enzyme in arthritic disease
Major enzyme in arthritic disease?
Aggrecanase 1&2 (ADAMTS 4&5)
What are the three histological hallmarks of OA?
- surface fibrillation due to o’clast activity
- chondrocyte cluster formation
- proteoglycan content down (lack of staining)
What test can you use for the thumb disorder affecting the wrap-around region?
Finkelstein’s test: grab thumb and ulnar deviate; PAIN
Describe the thumb wrap-around disorder
De Quervains
Pain when making a fist, spasms, swelling over thumb
- Extensor pollicis brevis
- Abdutor pollicis longus
What happens following acute denervation?
Paralysis
Fibrillation
Repair or Loss of contractile proteins / excitability / atrophy
What secretes biglycan, decorin and fibromodulin?
Osteoblasts
What secretes collagen in bone?
Osteoblasts
Biglycan
Secreted by o’blasts
In lacunae (pericullar)
Bind GFs; regulate bone growth
2 CS’s or DS’s on protein core
Decorin
Secreted by o’blasts
Attach to collage fibril and regulate fibrillogenesis (size) via GAP REGIONS
Binds GFs and sequester them in ECM
1 CS or DS on protein core
Fibromodulin
Bind collagen fibrils to regulate fibrillogenesis (size)
3-5 KS on protein core
What is pseudoachondroplasia
COMP protein mutations
Short-limb dwarfism
Scurvy
Lack of vitamin C = mpaired collagen synthesis
Collagen fibres fail to produce HYDROXYLYSINE and HYDROXYPROLINE so fail to form triple helices and are immediaely degraded
Vessels / bones become fragile
Osteogenesis imperfecta
Weak bones that easily fracture + neurological problems
Due to type I collagen deficiency
Chondrodysplasias
Abnormal cartilage; bone and joint deformities
Type II collagen deficiency
Ehlers danlos
Hyperflexibility, hypermobility, stretchy skin and vessels, easily rupturing skin and vessels; high risk for aortic aneurism etc
Type III collagen deficiency
Glycoproteins that regulate bone mineralisation?
Osteopontin, nectin, calcin
Bone morphogenic proteins?
Stimulate bone/cartilage formation
What effects does HIIT have on muscle?
Fibre hypertrophy
Increased glycolytic enzymes
–> increased power
What effects does aerobic exercise have on muscle?
Increased mitochondria
Increased capillaries
-> increased resistance to fatigue
What causes peripheral fatigue?
AP conduction failure - lack of calcium
Increased H+ due to lactic acid / ATP
Increased ADP
Cramp…
Nerve APs firing at v high rate causing painful and fast onset muscle contraction
Due to metabolic / ischaemic disturbance
Strains grading
1 = pain 2 = pain weaknes 3 = pain weakness LOF
Cartilage in ageing?
Aggrecan changes: decreased K6S:K4S
Decreased cell metabolism: shift to degradation
X-linking of collagen fibres (to compensate)
IX synthesis decreases: decreased sheer resistance
Increased cellular waste
What type of cartilage is articular cartilage made from
hyaline
What collagen type are sharpeys fibres
III
How much of the body calcium / phosphate is stord in bone
99%
Where is fibroC found?
IV discs, menisci
Where is elastic cartilage found?
ear pinna
Where is hyaline found?
Tips of long bones, trachea
What do chondroblasts secrete?
Collagen fibres
Ground substance e.g. solutes for water
How do chondroblasts become chondrocytes?
Surround themself in ground substance and fibres, pack themself into a lacuna then change to CCs
What is ground substance in bone made up of?
Osteoid
Calcium hydroxyapatite
