Pathokin Quiz 1

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67 Terms
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what is kinematics
descriptors of motion: linear and angular displacement, acceleration, and velocity
what is kinetics
descriptor of motion caused by torque and force
Kinematics describes _____ of motion
kinetics describes ____ of motion
equations for force
F= ma, Sigma F = 0
equations for Torque
T = F x moment arm, T = moment of inertia x angular acceleration
equation for work
work = force x distance
Equation for power
P=W/t (work/time), P = F x V
Equation for friction
Ffᵣ = μ Fɴ
what is the coefficient of friction
the roughness of a surface
What is a first class lever?
The fulcrum (joint) lies between the resistance arm and the muscle force
what is an example of a first class lever?
what is a second class lever?
The resistance force is in the middle, the fulcrum is on one end and the muscle force on the other (like a wheelbarrow).
what is an example of a second class lever
calf raises
what is a third class lever ?
Muscle force is between the axis of rotation and the resistance force
what is an example of a third class lever?
bicep curl
what lever is most common in the body?
third class
what are the four vectors of an external force?
length, direction, point of application, line of action
T/F: articular cartilage is avascular and aneural
T/F: degeneration of articular cartilage is painful
False: it's aneural
T/F: articular cartilage has poor healing capacity
True: it's avascular
synovial fluid functions
lubrication, nutrient distribution, shock absorption, diffusion of gases
T/F: Proteoglycans are hydrophobic.
False: they are hydrophilic which allows fluid to easily enter cartilage
load bearing surfaces separated by lubricin molecules; most effective with low joint bearing
Fluid Film
load bearing surfaces separated by film of lubricate maintained under pressure; most effective with high joint bearing
does wear and tear on cartilage increase or decrease the coefficient of static friction?
T/F: cartilage is most permeable during low stress and strain
T/F: cartilage tends to stiffen with increasing rates of loading
T/F: synovial fluid is thixotropic
True: it means viscosity varies inversely with joint velocity and temperature
Increased joint temperatures _____ fluid viscosity
what is chondromalacia?
softening of cartilage; can happen due to injury or defects
characteristics of osteoarthrosis?
articular cartilage erosion, which becomes soft, frayed, and thinned.
Three joint classifications
synarthrosis, amphiarthrosis, diarthrosis
Diarthrosis joint characteristics
Joint space filled with synovial fluid, most flexible
concave-convex: rolls and slides in the _____ direction
convex-concave: rolls and slides in the ____ direction
Close-packed position
maximum contact between the two joint surfaces, minimal mobility
Loose-packed position
less contact between the two joint surfaces; more mobility
T/F: the ultimate strain in most tendons and ligaments is approx 8-14%
True: after that, there could be a rupture
Tendons and ligaments are (stronger/weaker?) in compression
tendons and ligaments are (stronger/weaker?) in tension
T/F: when the muscle is relaxed there is crimp
T/F: when there is crimp, the sarcomere has minimal overlap of thin and thick filaments
What can torsion force cause?
spiral fracture
equation for stress
What is osteoporosis?
decrease in bone density, increase in bone porosity
Wolff's Law
A bone grows or remodels in response to forces or demands placed upon it
T/F Bone is strongest when it is in tension.
T/F bone is strongest when its in compression.
T/F bone is weakest in shear force
what is stress relaxation?
Decrease in the stress of a tissue in the presence of a constant strain
what is creep?
gradual strain of a tissue over time as the tissue is subjected to a constant load
equation for strain %
change in length/ original length
when is torsion most common?
with excessive training
What is a bone avulsion?
ligament get's torn out of bone
T/F: Low loading/ less stiff = bone avulsion
T/F: High loading/ more stiff = ligament tear
potential strength a muscle can generate is directly proportional to
its physiological cross sectional area
Collagen fibers become (disorganized/organized?) when ligaments maintain a stress-reduced position in immobilized joints. Recasting the joint in a position in which the tendon or ligament is elongated and stressed (or by stretching or strengthening exercises) can reverse the fiber (disorganization/organization) and help maintain the strength and biomechanical integrity of these tissues.
disorganized, disorganization
How long is electromechanical delay?
10-15 miliseconds
what is electromechanical delay?
time between arrival of a neural stimulus and tension development by the muscle
size principle of motor unit recruitment
small motor units are recruited 1st, then successively larger units begin firing as tension increases
T/F: Longer fusiform muscles (eg, sartorius) are better designed for force production
False: better designed for speed and ROM
T/F: shorter penniform muscles (eg, gastroc) with a high PCSA are better designed for speed and ROM
False: better designed for force production
what is the function of the golgi tendon organs?
autogenic inhibition
steps of autogenic inhibition
Motor neuron stimulation, muscle tension, force on tendon, stimulation of GTO, stimulation of inhibitory neurons
what do muscle spindles monitor?
Length of muscle / rate of change of length of muscle; how much and how fast you stretch