bio 442 exam 1
what can you apply to a lever to lift or work against a resistance
effort
class 3 lever
effort is between the fulcrum & load
what does creep contrast from
elastic material which doesn't exhibit an increase deformation no matter how long the load is applied
2 functions of having elastin in ligaments
elastic protein store & recovery energy
toe region of tendons
elongation accompanied by very low stress initial low stiffness
measurement of material properties in tendons
end effect, toe region problem, grip
when an interaction ceases, the 2 objects do what
no longer experience the force
orientation of collagen fibers of woven bone
random
work & power
rate at which energy is transferred is an important performance vector
steroids & exercise
rate of muscle growth doesn't allow tendons enough time to adapt
plastic region
region after the yield point, before failure
what does a non-linear s-s curve neglect that other graphs do not
viscoelastic behavior
what do proteoglycans influence in ligaments
viscoelastic properties
delta x =
vit + 1/2at^2
tangental velocity =
w (angular velocity) x r (position vector)
what type of axis does bending create
neutral
articular cartilage doesn't have what
blood, lymph nodes, & nerves
calcified zone transitions into what
bone
what has more proteoglycans
bone
what property is rarely seen with pure tension
bone
chondrocytes are responsible for what
cartilage formation
degree to radians
(given degree)(pi/180)
radians to degree
(radians)(180/pi)
Egi =
-mgh
at physiological stresses when can a rupture not occur after
15 days
what type of collagen is mostly in articular cartilage
2
how much water are in ligaments
2/3rds
by 90 years old, how much % of bone to women loose
20% cortical & 50% trabecular
how much to compressive properties of cartilage vary by depth
20x (due to proteoglycan content or collagen fiber arrangement)
what class of levers are most joints
3
peak bone mass is obtained before what age
30
failure % of stress at 40 weeks from ligament scar material
35
how much % of bone's dry weight is organic
35
ostotendinous junction components in cancellous bone
4 layers (normal tendon, fibrocartilage, calcified cartilage, bone)
how much % of people have osteoarthritis when over 60 years of age
50
how much of bone is evolutionary conserved across mammals
63-70%
failure % of force at 40 weeks from ligament scar material
65
how much % of bone's dry weight is mineral
65
how much % what is articular cartilage
65-80
what % of collagen contributes to the dry weight of ligaments
70-80
gravity on earth's body
9.81 m/s2
how much % of the organic matrix is collagen
95
stress =
F(internal force)/A(cross-sectional area)
work units
J
W is equivalent to what
J/s OR Nm/s
J is equivalent to what
Nm & kg m/s2
impulse units
Ns
what does a lever amplify
an input force to provide a greater output force
forces only exist as a result of what
an interaction
power units
W (watts)
an impulse represents what
a change in momentum
magnetic force
a consequence of the electromagnetic force
what is the transition from tendon to fibrocartilagneous tissue characterizes by
a dense proteoglycan sound substance
according to newton's 2nd law since there is an acceleration in centripetal force there must be what
a force inwards
whenever there is an interaction between 2 objects what is there
a force upon each of the objects
kinematic equations describe motion as what
a function of time
creep failure in tendons
a material fails under prolonged contact stress
what is a class 2 lever also called
a multiplier force
what are chondrocytes surrounded by to protect the cell
a perpendicular matrix
primary bone needs what
a pre-existing substrate
woven can be deposited fast without what
a pre-existing substrate
force
a push or pull upon an object resulting from the object's interaction with another object
during a collision, an object experiences a force for what
a specific amount of time
best control involves what
a stiff tendon
what does the connection between the golgi tendon organ & the tendinous fascicles send
a thick, myelinated afferent fibre to the spinal cord
example of motions in the frontal plane
abduction & adduction
when do fibroblast appear in ligament healing
about a week
example of anisotropy
absorbance
how does menopause affect bone loss
accelerates it
law of acceleration
acceleration is produced when a force acts an a mass (f=ma) the greater the mass, the greater the amount of force needed to accelerate it
risk factors for osteoarthritis
age, obesity, genetics, injury
volkmann's canal
all osteons & smaller & perpendicular to bone
why is injury a risk factor for osteoarthritis
altered loading (unloading & overloading of involved & uninvolved)
contact area in the joint increase when what occurs
an increase in force application
law of interim
an object @ rest will remain @ rest unless acted upon by an unbalanced force an object in motion continues in motion with the same speed & in the same direction unless action upon by an unbalanced force
rotation is what type of motion
angular
torque is required for what type of acceleration
angular
internal tendon
aponeurosis portion of tendon inside tendon looms like a sheet
types of contact forces
applied, normal, tension, air resistance, friction, spring forces
scaling
area increases as length2 mass increases as length3 mass increases etc
toughness
area under the s-s curve
flaws of scar morphology
areas will have holes which will increase stress concentration which is present at 14 weeks
when is the gap closed during ligament healing
around 3 days
fiber alignment is normalized when
at 14 weeks
objects included in mechanics
atomic particles in the universe
4 ligament functions
attached articulating bone across a joint, guide joint movement, maintain joint congruency, & proprioception
efferent
away from CNS
where is the toe region on a s-s curve
beginning
what 2 stresses are the most common combined loads in the skeletal system
bending & compression
haversian canal
bigger than vascular channel in primary osteon
is diffusion or blood a more efficient way to transfer nutrients
blood
blood cells with ligament healing
blood cells with clot initially
ligament structure order
bone --> calcified fibrocartilage --> fibrocartilage --> ligament
osteoblasts
bone producing cells/immature cells
if bone was just cortical what would happen
bone would be heavier
how are ligaments & tendon similar structurally
both have similar hierarchal structures with successive bundles
fast strains are more likely to what
break bone
osteoclasts
break down & absorbs
woven bone comes from what
broke bones
what type of bone is irregular/short bones composed of
cancellous
toe region problem in tendons
cannot find the zero point & can make definitions hard
torque
capability of a force
which has more proteoglycans - cartilage or ligaments
cartilage
muscle weakness could be related to what
cartilage degeneration
what is organic material of the bone
cells & water
velocity =
change in position/change in time
how to calculate movement
change in positon/change in time
acceleration =
change in velocity/change in time
2 ways to bring a lever to equilibrium
change mass & distance
tendons & disuse
changes are largest near the muscle muscle tendon junction is weaker decreased collagen production smaller collagen fibers
examples of potential energy
chemical, gravitational, elastic
cells on articular cartilage
chondrocytes
following an injury what do chondrocytes do
cluster & produce the matrix
friction =
coefficient of friction (u thing) x normal force (N)
scar biochemistry in ligaments
collagen cross linking stronger when more interconnection between ropes scar tissue cross linking dramatically reduced cross link density is 50% at 40 weeks
when the muscle contracts tension is transferred to the tendon causing what
collagen fibers to compress the nerve & initiate action potentials
linear region of the non-linear s-s curve
collagen fibril backbones becoming stretchy yielding a stiffer material
what 3 things make up the cartilage matrix
collagen, proteoglycans, & other proteins
examples of spring like material in the human body
collagen, tendons & ligaments, skin, & foot
mechanical properties of bone
combination of the structural & the material properties of bone
what type of material is bone
composite material
articular cartilage is loaded in what
compression
how do bones typically load
compression force
3 mechanical properties of cartilage
compressive, tensile, & shear
articular cartilage is a network of what
connective protein
synovial sheath
connective tunnel the tendon moves in holding tendon close to the joint structure
the multilayered fibre bundle organization of a tendon allows for the maintenance of high tensile strength with what
considerable flexibility in bending
3 types of forces
contact, non-contact, & centripetal forces
compliant tendons complicate what
control
2 types of bones
cortical & cancellous
3 types of viscoelastic elements
creep, stress relaxation, & rate dependency/hysteresis
what pattern do ligaments have
crimp
calcified zone function
decrease stress concentration
how does aging affect cellularity in ligaments
decreased
tendons & aging
decreased cross-sectional area increased cross-linking more small fibers no change in modulus more prone to fatigue failure
smaller collagen fibers -->
decreased material properties
articular cartilage helps with what
decreasing friction
which zone has the highest proteoglycan concentration & lowest water content & permeability
deep zone
which zone is best at resisting compressive loads with a poisson ration of 0.5
deep zone
creep increases what
deformation under a constant load
strain =
delta L/L(length)
kinematics
description of motion which includes the consideration of time, displacement, velocity, acceleration, & space
diaphysis
develops from primary ossification (shaft) the hollow shaft of a long bone, made up of cortical bone & usually contains bone marrow & adipose tissue surrounded by medullary cavity
highly organized structure each right with fibers aligned in what
different directions to force
vectors have what
direction & magnitude
example of vectors
displacement, velocity, weight, gravity, force, & acceleration
example of scalars
distance, mass, speed, density, time, length, area
moment of inertia
distribution of mass within an object tendency for a body to resist angular acceleration
levers apply what to a load
effort
3 ways to measure material properties in ligaments
end effects, ligament cross-sectional area, & zero strain. position
what are fascicles surrounded by
endotenon ( a ct sheathe with proteoglycans & elastin & contains blood, lymphatic vessels, & nerves)
1st law of thermodynamics
energy cannot be created or destroyed, only transformed from 1 from to another
work
energy transferred to or from an object by application of a force
what are fascicle bundles surrounded by
epitenon
who was the pioneer for biomechanics
etienne jules mary in 1880
what would happen if normal force did not exist
everything would collapse on itself
what is a consequence of the folded structure of the myotendinous junction
facilitate the transfer of land by shear rather than tension which creates an acute angle of contact between muscle & tendon tissues
fatigue failure in tendons
failure of material subjected prolonged cyclical loading
fascinates aggregate into what
fascicle bundles
fibre bundles are aggregated to form what
fascicles
medullary cavity
fat storage site lined by a thin, largely cellular ct membrane not in flat bones
what 4 aspects reduce after disuse in ligaments
fiber #, collagem content, cross linking, & glycoproteins
hierarchal bundling is a classic organization pattern for what
fibers experiencing tension along a long axis
3 components of scar morphology
flaws, fiber alignment, & fiber size
example of motions in the sagittal plane
flexion & extension
what are some tendons enclosed by
fluid filled synovial sheath
canaliculi
fluid filled, forces supply lacunae with nutrients, viscoelastic activity
law of action & reaction
for every action, there is an equal & opposite reaction whenever an object pushes on another object, it gets pushed back equally hard in the opposite direction
strain
force normalized to deformation
stress
force normalized to the amount of material
air resistance
force of air pushing back on an object
friction
force resisting things sliding over one another like solids, liquids, etc
gravitational force
force that one body exerts on another/refers to the pull of earth on the body
tension
force transmitted through a string or rope (or biological tissue) when it is pulled from either end
work =
force x distance
bones need what
forces
wolffs law
forces present cause shape & if a force is present change will occur
sagittal/longitudinal plane
front & back
cyro-grips
frozen material/dired material behave differently then life tissue
class 1 lever
fulcrum is between the effort & load
holes in the cartilage structure affects what
function
what happens to proteoglycan content after an injury
generally does not recover
how is the transition from the spindle shaped tendon cells to rounded cartilage chondrocytes
gradual
types of non-contact forces
gravitational, electricostratic, magnetic
mechanical advantage of a class 2 lever
greater than 1
mechanical advantage of a class 1 lever
greater than, less than, or equal to 1
what is the purpose of having a fluid filled synovial sheath
greatly reduced friciton
metaphysis
growth zone
proteoglycans hold onto what
h2o
what happens during cyclical loading that leads to fatigue failure in the tendons
h2o can't get back in & will fail at a stress
the more dense -->
handle stress better
4 types of spaces in bone
haversian canal, volkmann's canal, lacunae, & canaliculi
exercise causes what with chondrocytes
helps chondrocytes to produce the matrix
where are contact areas when we are the strongest
high at the joint angles
stiffer spring -->
higher restoring force
parallel fashion -->
higher tensile strength in cartilage
how organized is primary bone
highly
proteoglycans
hold onto water, protein core, side chains containing sugar
simplest kind of spring
hookean spring
what is crucial to understanding biomechanics
how an organism moves & the diversity of locomotion
velocity
how fast & what direction
speed
how fast something is going
what does momentum depend on what
how fast something is going & how much it is going
angular momentum =
i (moment of inertia) times w (angular frequency)
hysteresis
if a viscoelastic material is loaded & unloaded, the unloading curve will not allow for the loading curve
area under the grf curve
impulse
what happens to bone resporation at the insertion site due to disuse
increased
age & cartilage relationship
increased age, decreased cartilage strength
how does exercise increase ligament strength
increased fiber #, collagen content, cross linking, & glycoproteins
why is obesity a risk factor for osteoarthritis
increases the load & could possibly change the chemical composure
what occurs due to the longitudinal folding in the myotendinous junction
increases the surface area contact by 10-20x, sometimes even 50, which transfers the stress from muscle to tendon greatly
intensive property
independent of the size of the system & does not depend on the amount of material
yield & failure region of a non-linear s-s curve
individual fibril begin to fail damage accumulates stiffness is high
where is the myotendinous junction typically located
insertion & origin end of the muscle belly
actin cytoskeleton
inside cell protein actin forms filaments that provide cells with mechanical support & driving forces for movement actin contributes to biological processes such as sensing environmental forces
how are position & motion linked
instantaneously
2 pathways of sensing in cartilage
integrins & actin cytoskeleton
what sized objects are in newtonian mechanics
intermediate sized (biological realm)
how are collagen fibers organized in ligaments
into bundles & oriented between insertions
when an object is at a different position what happens
it has been displaced & a motion has occurred
cartilage models
it is nearly impossible to measure in vivo mechanics
tendon's high tensile stiffness & strength of a tendon is attributed to what
its relatively high collagen content (70-80% dry weight) & its hierarchical organization into linear bundles
units of momentum
kgm/s
2 typed of energy
kinetic & potential
Hooke's law f=
kx
scaring in ligament healing
larger cross-sectional area more material but a lot weaker when evaluated as a material property
what newton's law is mechanical advantage similar to
law 3 - law of action & reaction
newton's 2nd law
law of acceleration
newton's 3rd law
law of action & reaction
newton's 1st law
law of inertia
what 2 factors affect effective mechanical advance
length of the moment arm & mass
how does aging affect the collagen crimp in ligaments
less crimp --> decreased toe region
mechanical advantage of a class 3 lever
less than 1
where are golgi tendon organs
lie within a tendon & close to the myotendinous junction
what has more collagen
ligaments
what human material properties have a toe region
ligaments & tendons
example of spring forces
ligaments/tendons with shock absorption & energy storage
force is required for what type of acceleration
linear
translation is what type of motion
linear
is the function of proteoglycans the same in both cartilage & ligaments
nah
what will be the result of if a tendon is cyclically stretches & allowed to recoil within the range of reversible strain
load deformation measurements form a loop
class 2 lever
load is between the effort & the fulcrum
torsion
loading that results from twisting & can give shear stress magnitude of the stress is dependent on the size & shape of the object in the cross-section
materialas deform in response to what
loads
grip in tendon
location of stress concentration wider clamp variety because they are longer than ligaments cyro-grips
what type of projections do osteocytes have
long projections like neurons
what type of folding of the tendon into the muscle cells occur in the myotendinous junction
longitudinal
stiffness in the toe region
low
tendon has _______ hysteresis
low
how much friction is in the environment of a tendon
low amounts
proteoglycan content in the superficial layer
low content
synovial fluids acts as a what
lubricant
scalars have what
magnitude
increased mineralization -->
make bone stronger but make them more likely to break
osteocytes
mature osteoblasts (ones that get trapped in the bone)
disuse of cartilage reduced what
mechanical stimulation, reduced nourishment to the cells, & a reduction in proteoglycan synthesis
periosteum
membrane outside (source of stem cells)
which zone of cartilage is the most metabolically active
middle
2 types of % of dry weight in bone
mineral & organic
is bone static
nah, will break down if they aren't used
what happens to momentum if there is a perfect collision (no energy less due to friction, air resistance, heat, etc)
momentum is conserved
proteoglycan content of middle zone
more & less water than the superficial zone
why are tendons better at resisting tensile forces than ligaments
more elastin than ligaments
stress fracture
more osteoclast activity than osteoblast
more extensive property -->
more property
what does the increased cross linking & collagen content cause in adapting to aging in ligaments
more small gibers, decreased water content, decreased ultimate stress
what does secondary bone have that primary has less of
more space for vascular structures for nutrients
dishes causes what in the bone
more spaces in the bone
what would happen if bone just directly attached to ligaments without fibrocartilage
more stress
combined loads
most loading is a combination of different mechanics
what type of fibers are the collagen in ligaments
mostly 1
collagen
mostly type 2 fibers long ropes of protein
what does a force cause
motion
y parameter of kinematic equations
motion
what does newton's law of motion explain
motion & how forces result in movement
examples of kinetic energy
motion, heat, sound
how to adjust the length of a moment arm
move the center of mass / limb position
how does scaring of the ligament impacts viscoelastic properties
much inferior & h2o leaks out
fatigue failure is unique to what 2 material properties in the body
muscle & tendons
example of tension
muscle pulling on a tendon
golgi tendon organs are mechanoreceptors that monitor what
muscle tension
does kinematics involve force
nah
centrifugal force
not a real force rather the apparent force that occurs when you exert a centripetal force
end effect for tendons
not as effective as in ligaments
fiber size & scar morphology
not normal at 40 weeks smaller than native ligament
tensile stress
occurs as a result of a force that is pulling apart an object
shear force
occurs perpendicular to tension or compression & slides molecules of the object past each other
cancellous bone
oriented primarily in the direction of the forces applies to the bone organized to withstand mechanical loads while minimizing weight of the bone
excessive loading can lead to what
osteoarthritis
lacunae
osteocytes & creates spaces when trapped
1-2.5 standard deviation below average
osteopenia
>2.5 standard deviation below average
osteoporosis
what are cement lines in secondary bone
outside edge hardened & is the joint between 2 bone types
external tendon
outside muscle cord
tendonitis
overuse equivalent to the stress
superficial layer are arranged how
parallel
where do the majority of collagen fibers lie
parallel to the long axis of the tendon
what are several fascicular bundles surrounded by
paratenon (outmost tendon sheath)
units of poisson ration
pascals
units of stress
pascals
the deep collagen fibers of the tendon do what
penetrate the periosteum & attach directly into the bone
how are fibers arranged in the deep zone
perpendicular
anisotropy
physical or mechanical proper of a material which allows it to change or assume difference
examples of biomechanics application
physical therapy, prosthetics, joint replacement, car crash, ergometry, & sports performance
what is secondary bone very much like
primary osteons
viscoelastic properties
property of material exhibit both viscous & elastic characteristics when undergoing deformation
ligament cross-sectional area
proposed decrease csa with stretch (poisson ration) difficult to declare true csa
momentum
quantity of motion of a moving body, as a mass is in motion
3 types of mechanics
quantum, relativistic, & newtonian
torque =
r (distance from center of rotation) times F (force)
osteotendinous junction components in cortical bone
relative high stress concentration, superficial fibers blend into periosteum, & deep fibers penetrate bone
to transmit force from muscle to bone what does the tendon need to be
relatively stiff & strong in tension but be able resist deformation
cartilage has a limited ability to what
remodel
viscous material
resist shear flow & strain linearly with time when stress is applied
secondary bone is the product of what
respiration of previous bone
statics has constant what
rest or acceleration
tenosynovitis
rom swelling mechanism
example of motions in the transverse plane
rotation
3 planes
sagittal, frontal, transverse
example of a shear force
scissors
example of a class 1 lever
seesaw
the myotendinous may be stronger in what than in tension
shear
what mechanical property of cartilage is not fully understood as it is hard to test
shear
what stress are most materials are weakest with
shear
types of stress
shear, compression, shear, bending, torsion, combined, & strain
2 components of a stiff tendon
short tendon & big cross-sectional area compared to the muscle ration
frontal/coronal plane
side to side
interns
signaling proteins tied to the membrane that regulate growth, proliferation, migration, signaling, & cytokine activation & release
levers
simple machines that consist of a rigid beam or rod that pivots around a fulcrum
why it is crucial to have trupoclalegn & microbial helices
since they have different direction helices it keeps the material from unwinding when loading
adaptation from exercise in tendons are what
site specific
example of static mechanics
sitting
what do chondrocytes mimic
skeletal development
shear properties are very what
slippery
epiligaments
smaller collagen fibrils, oriented more randomly very cellular protection/friction reduction support nerves & blood vessels
why must axial vectors all be parallel to the axis of rotation
so only the magnitudes of the vectors are necessary
cortical bone
solid, dense material composing the walls of diaphysis & external surface of bone & external surfaces of bone
relatively flat plastic region
some fibers stretch more considerable yield region in which tendon deformation is accompanied by very little increase in stress fairly high ultimate strength
example of dynamic mechanics
someone sprinting off the line
what type of element is associated to motion
spatiotemporal
what are golgi tendon organs comprised of
specialized nerve ending that air in a series with the contractile proteins of the muscle
golgi tenon organ summary
specialized nerve endings found near myotendinous junction in series with muscle fibers are compressed when muscle contracts have highly myelinated afferent neurons relay info back to the central nervous system about contraction levels in the muscle cause inhibition of contraction
what is a class 3 lever also called
speed multiplier lever
k
spring constant
hooke's law describes
springs
why is the type of loading with cartilage important
static loading --> bad intermittent loading --> good fluid flow
example of isotropy
steel
elastic material
strain when stretched & immediately return to their original state once the stress is removed
ratio between compact vs spongey bone determines the balance between what
strength & mass
end effects
stress concentration at point of grip can result in inaccurate point of measurement
stress relaxation
stress will be reduced or will relax under a constant deformation
young modulus (E) =
stress/strain
material properties of bone
structural properties of bone refer to the organization of compact or cortical bone & the spongey or trabecular bone
what happens to proteoglycans when one ages
structure changes sugar is shorter & has less water content there is a shorter core & side chain
dynamics
study of systems in motion with acceleration
statics
study of systems that are in a constant state of motion, whether at rest with no motion or moving at a constant velocity without acceleration
kinetics
study of the forces associated with motion of a body/forces acting on an object
objects excluded in mechanics
subatomic, objects moving at the speed of light
what zone are tensile properties are higher
superficial
what of the tendon blend in with the periosteum in cancellous bone
superficial collagen fibers
4 layers of articular cartilage
superficial, middle, deep, calcified
slow strains are more likely to what
tear ligament
what has more elastin
tendon
3 types of tendon injuries
tendon adhesions, tendonitis, & tenosynovitis
what are visible at the fascicular level of tendon organization that are longitudinally aligned among fibre bundles
tendon cells
tendon healing
tendon is somewhat vascular however the healing process won't be complete
exercise can increase what in tendons
tendon size & collagen content
what 2 properties are often loaded with pure tension
tendons & ligamanets
ligaments have a hierarchical structure arranged between insertions to resist what
tensile forces
collagen on the outside of the cartilage is loaded in what
tension
compression force is opposite of what stress
tension
golgi afferent synapse inhibit what during isometric contraction
the alpha motion neurons of the corresponding muscle
what does the difference between the 2 curves in hysteresis represent
the amount of energy that is dissipated or lost during loading
poisson ration
the amount of material in an object is fixed thus if an object is stretched it will get thinner or if an object is compressed it will bulge out
endosteum
the ct membrane lining medullary cavity (inside)
how do chondrocytes receive nourishment
the diffusion
synovial fluid permits what
the diffusion of gasses, nutrients, & waste
what do material properties often vary in
the direction in the the material in which they are measured (referred to as anisotropy)
mechanical advantage
the efficiency of a lever
why is the mechanical advantage of a class 3 lever less than 1
the effort arm is smaller than the load arm
epiphyses
the end part of a long bone, initially growing separately from the shaft (secondary ossification)
normal force
the force acting perpendicular to the surface on which an object sits
spring forces
the force exerted by a stretch or a compressed spring or any object attached to it
elastic region
the linear region where the material can deform without resulting in permanent change
why is the mechanical advantage of a class 2 lever greater than 1
the load arm is smaller than the effort arm
young modulus can be tested in multiple directions depending on what
the material
ultimate strength
the max amount of s & s the material can sustain prior to breaking
biomechanics
the mechanics of biological objects & physical worlds interacting
what makes the tropocollagen molecules enhance the tensile properties of the tendons
the molecules in the heavily cross linked regions of the fibers are crystallized
yield point
the point where material cannot revert to the original form
power
the rate at which work is done (energy per unit of time)
what defines a lever
the relationship between the fulcrum, effort, & load
electrostatic force
the repulsive/attractive interaction between any 2 charged bodies
for adhesive joints it is desirable to maximize what
the shear component of loading
young modulus
the slope of the line approaching the yield point
golgi afferent synapse with the interneurons of where
the spinal cord
mechanics
the study of the motion of objects
what does each golgi tendon organ connect to
the tendinous fascicles associated with approx 10 muscle fibers
for adhesive joints it is desirable to minimize what
the tensile component
what 2 things does the lever change
the torque exerted & the distance moved by an object
failure strength
the value in which the material "breaks"
things get heavier faster than what
they get stronger
what happens to ligaments at insertion from disuse
they will fail
applied forces
thing push or pulling on another object
evolutionary advantage of proximally distributed le mass
things that are good runners tend to move mass more proximally in the limbs
how do some tendon cells get nutrients
through diffusion partially inside the synovial sheath
x parameter of kinematic equations
time
why does bone need to be sufficiently rigid
to provide the necessary support & force transfer but also capable of deforming enough to absorb the energy of an impact before breaking
afferent
to the CNS
zero strain position
toe region make it difficult to know where the strain begins
components of a non-linear s-s curve for ligaments
toe region, linear plastic region, & relatively flat plastic region
transverse plane
top & bottom
bending
torsion on 1 side & compression on the other very common loading condition
what is cancellous bone formed by
trabeuclae (thin bony spicules)
osteotendinous junction
transition from tendon to fibrocartilaginous tissue
middle zone arrangement
transitional zone with more random arrangement of fibers
functions of tendons
transmit force from muscle to bone, apply force to a relatively small content surface, & storage of elastic energy & return
functions of cartilage
transmit forces across joint, muscles pulling to create movement, distribute forces to minimize stress concentrations, & provide low friction surface
purpose of the structure of the calcified zone
transmit forces safely across the joint
primary role of a tendon
transmit the force of it associated muscle to bine
tendon adhesions
trigger finger/frozen
most basic unit of collagen
tropocollagen
tendon hierarchical structure
tropocollagen --> microfibrils --> sub fibrils --> fibrils --> fibres --> fibre bundles
difference between tropocollagen helix & microfibril helix
tropocollagen has a left hand helix & microfibrils have a right hand helix
example of a class 3 lever
tweezers
why is an accelerating system unbalanced
unequal forces acting on the body
isotropy
uniform in all orientations
linear elastic region of tendon
used to calculate young modulus
what does the calcified zone have more than the deep zone
vascularization
what sized objects are in relativistic mechanics
very large (stars & blackholes)
what sized objects are in quantum mechanics
very small (atoms & subatomic particles)
vf =
vi + at
4 main structural components to ligaments
water, collagen, proteoglycans, elastin
what does a random orientation of collagen fibers cause
weakness
example of a class 2 lever
wheelbarrow
centripetal force
when an object is moving around a circle, the linear velocity is constantly changing directions but not magnitude
when is crimping 1st apparent in tendons
when fibre aggregate to form fibre bundles
when is a lever balanced
when torque 1 = torque 2
example of stress relaxation
when you bend over, your flexor & extension muscles cannot both be fixed
extensive property
whose magnitude is additive for subsystems
power =
work/time
what axis is strain on
x
cos =
x/r
what axis is stress on
y
sin =
y/r
tan =
y/x
can the young modulus revert back
ye
does helical interweaving vary among structural levels
ye
does kinetics involve force
ye
does the transition within the osteotendinous junction differ in cortical & cancellous bone
ye
is cartilage mechanosenstitive
ye
can bone deform
yes since it has water content in it which makes it viscoelastic
can you stretch the toe region of a graph
yes, it is easy to stretch initially due to the crimp pattern
example of a centrifugal force
you feel like you're getting thrown off a ride
the variation of the calcified zone in a cellular environment is thought ti influence what
zonal changes rather than a discrepancy between cells
what happens in the superficial layer
zone is permeable & though to contribute ute to signaling successive zones
