Pathokin Quiz 1

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

characteristics

kinetics describes ____ of motion

cause

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?

skull

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

true

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

boundary

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?

increases

T/F: cartilage is most permeable during low stress and strain

True

T/F: cartilage tends to stiffen with increasing rates of loading

True

T/F: synovial fluid is thixotropic

True: it means viscosity varies inversely with joint velocity and temperature

Increased joint temperatures _____ fluid viscosity

decreases

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

same

convex-concave: rolls and slides in the ____ direction

opposite

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

weaker

tendons and ligaments are (stronger/weaker?) in tension

stronger

T/F: when the muscle is relaxed there is crimp

True

T/F: when there is crimp, the sarcomere has minimal overlap of thin and thick filaments

True

What can torsion force cause?

spiral fracture

equation for stress

force/area

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.

False

T/F bone is strongest when its in compression.

True

T/F bone is weakest in shear force

True

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

True

T/F: High loading/ more stiff = ligament tear

True

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