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What is a force applied per unit area?
stress
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What term is used when stress produces a change in length of a structure?
strain
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What is the formula for % change in length?
change in length over original length
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Very little force if required to elongate the tissue, but as more force is applied, the % of elongation does what?
decreases
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What are the 3 stages to structural lengthening?
elastic, plastic, and rupture
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What happens during the elastic portion?
requires little force and time, after the phase the structure will return to the normal shape -rubber band
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What happens during the plastic portion?
requires more force and time, when phase is over the gained length is lost almost instantly, however a portion of it remains permanent (doesnt completely go back to original shape) -balloon
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What portion requires little time and force?
elastic
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What portion requires more time and force?
plastic
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What happens during the rupture portion?
the structure fails - car accident, repeated strain and stress; runners, sprained ankle...
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Tissues respond to what 5 things dealing with stress?
- compression
- tension
- shearing
- torsion
- bending
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What is compression?
compressive forces making things shorter
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What is tension?
elongation of tissues - traction force
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What is shearing?
side to side (sliding) force, parallel surfaces sliding
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What is torsion?
twisting, rotary force, using lots of planes
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What is bending?
angular motion, onmly using 1 plane
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Bodies need a certain amount of what to be healthy?
stress
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What is chondrogenesis?
inital loading, building cartilage (when baby)
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What is osteogenesis?
continual loading, making bone (exercise)
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What is the functional adaption of bone to stress?
Wolff's law
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What is the forces that occur in bone that cause the bone to grow and thicken better than tension (elongating)?
compression
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What in bones will start to have a negative effect?
increased compression
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What helps increase bone density, but if you go overboard will cause body damage?
high intensity exercise
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What can cause a change in direction of growth caused by compression or structural problems?
unequal loading
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What is the name for knock kneed?
genu valgum
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What is the name for bow legged?
genu varum
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What causes bone fractures?
rapid overload
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How does normal tension affect cartilage?
cartilage needs normal healthy stress and strain, it will become thicker and stronger
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What results in degeneration, tearing, or fraying of cartilage?
excessive compression (knees receives a lot)
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What happens in the absence of compression in cartilage?
results in atrophy
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What leads to tearing or fraying in cartilage?
rapid or chronic overload
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What does a ligament connect?
bone to bone
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What does a tendon connect?
muscle to bone
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In ligamentsand tendons, what increases size, thickness, and strength?
normal overload of tension
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If there is a lack of loading after immobilization, what happens?
atrophy, decreased strength...set yourself up for injury
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What does a healthy load of exercise do to tendons and ligaments?
increase size and strength
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What is the "stretch/creep rule"?
stretching/lengthening; serial casting (repeat casting after gaining new length)
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What is better for artificial joints or ligaments?
natural material bc its stronger and better than man made
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