stress & strain.txt
Card Set Information
stress & strain.txt
lecture 4, 10-3-11
What is a force applied per unit area?
What term is used when stress produces a change in length of a structure?
What is the formula for % change in length?
change in length over original length
Very little force if required to elongate the tissue, but as more force is applied, the % of elongation does what?
What are the 3 stages to structural lengthening?
elastic, plastic, and rupture
What happens during the elastic portion?
requires little force and time, after the phase the structure will return to the normal shape -rubber band
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
What portion requires little time and force?
What portion requires more time and force?
What happens during the rupture portion?
the structure fails - car accident, repeated strain and stress; runners, sprained ankle...
Tissues respond to what 5 things dealing with stress?
What is compression?
compressive forces making things shorter
What is tension?
elongation of tissues - traction force
What is shearing?
side to side (sliding) force, parallel surfaces sliding
What is torsion?
twisting, rotary force, using lots of planes
What is bending?
angular motion, onmly using 1 plane
Bodies need a certain amount of what to be healthy?
What is chondrogenesis?
inital loading, building cartilage (when baby)
What is osteogenesis?
continual loading, making bone (exercise)
What is the functional adaption of bone to stress?
What is the forces that occur in bone that cause the bone to grow and thicken better than tension (elongating)?
What in bones will start to have a negative effect?
What helps increase bone density, but if you go overboard will cause body damage?
high intensity exercise
What can cause a change in direction of growth caused by compression or structural problems?
What is the name for knock kneed?
What is the name for bow legged?
What causes bone fractures?
How does normal tension affect cartilage?
cartilage needs normal healthy stress and strain, it will become thicker and stronger
What results in degeneration, tearing, or fraying of cartilage?
excessive compression (knees receives a lot)
What happens in the absence of compression in cartilage?
results in atrophy
What leads to tearing or fraying in cartilage?
rapid or chronic overload
What does a ligament connect?
bone to bone
What does a tendon connect?
muscle to bone
In ligamentsand tendons, what increases size, thickness, and strength?
normal overload of tension
If there is a lack of loading after immobilization, what happens?
atrophy, decreased strength...set yourself up for injury
What does a healthy load of exercise do to tendons and ligaments?
increase size and strength
What is the "stretch/creep rule"?
stretching/lengthening; serial casting (repeat casting after gaining new length)
What is better for artificial joints or ligaments?
natural material bc its stronger and better than man made