MIDTERM 1 Flashcards
kinematics vs kinetics
kinetics: describes motion of body in terms of FORCES i.e. all force, no mvmt
kinematics: describes motion using displacement, velocity, acceleration. NO FORCES
position
location of an object relative to a reference
a SCALAR quantity, has magnitude but no direction
scalar vs vector
scalar: magnitude, no direction
vector: magnitude and direction
moment of force
TORQUE, rotary effect of force
when a force is applied a distance away from the centre
the greater the distance away = bigger force = greater moment of force
spatial-temporal graph
time against vertical displacement
spatial-spatial graph
horizontal displacement vs vertical displacement
types of contractions
- concentric
- eccentric
- isometric
- isokinetic
- isotonic
isotonic vs isokinetic vs isometric contractions
isokinetic: mvmnt where angular velocity of displaced BODY SEGMENT is constant, i.e. equal torque. needs special machinery.
isometric: contraction where load = muscle, and no change in muscle length
- TM/TL = 1
- omega = 0, meaning angular velocity = 0
isotonic: contraction where muscle contracts and does work against a load i.e., concentric, eccentric contractions
concentric vs eccentric contractions
eccentric: load > muscle, the muscle cannot move load and muscle lengthens
- TM/TL < 1
concentric: load < muscle, muscle shortens as it moves load
- TM/TL > 1
- for either, omega = k, a constant
stress vs strain
stress: when a load is applied to a cross-sectional area
strain: when bone deformation occurs as a result of stress
types of stress
- torsion
- compression
- combined loading
- tension
- shear
- bending
tension stress-strain relation
E: elastic region
- quickly increasing, linear relationship
- can return to original shape
plastic modulus
- after elastic region
- SOME damage to the bone, but no fracture
- when in this region, more stress = EVEN MORE strain
- won’t return to exact shape
ultimate point: fracture
compression stress-strain relation
entire graph is “elastic region” until ultimate point
- why bones can withstand more compression
minimal strain compared to stress
types of fractures
- greenstick
- comminuated
- avulsion
- transverse
- oblique
- impacted
- fissure
- spiral
fracture caused by compression of bone
impacted
occurs in middle when bone buckles into self
common in children bcs bones not ossified
greenstick
bone bends rather than breaks
trapping of bone while other twists over i.e. foot in rock
oblique
fracture at sloped angle or curves
caused by force not strong enough to completely break bone
fissure/hairline
incomplete bone fracture, lines visible that don’t pass through bone
caused by crushing force
comminuated
fractures in multiple pieces
muscle contraction or stretch that’s stronger than the force that holds the tendon/ligament to the bone
avulsion
ligament/tendon pulls away from bone attachment, breaking off piece of bone
caused via bending force that snaps bone
transverse
fracture at 90 degree angle
structure of muscle
large –> small
- whole muscle
- muscle fibres
- microfibrils: smallest component of muscle fibres
- sarcomeres: repeating units
- myofilaments: includes myosin and actin
contraction cycle steps
- ATP hydrolysis: ATP broken down into ADP + Pi, energizes myosin head
- formation of cross-bridges. myosin head attaches to binding sites on actin
- power stroke: cross-bridge rotates, sliding filaments
- detachment of myosin from actin: when a new ATP binds to myosin head, it detaches from binding site to repeat cycle
what starts contraction cycle?
sarcoplasmic reticulum releases Ca2+ into muscle cell (stored in SR until nerve impulse)
calcium binds to troponin, making it move tropomyosin away from myosin binding sites
contractile proteins
myosin: converts ATP –> mvmnt –> force
actin: provides site for myosin head to attach
regulatory proteins
both proteins are on actin
tropomyosin: covers myosin binding site when at rest so head can’t attach
troponin: moves tropomyosin away from site when Ca2+ binds to it
structural proteins
myomesin: forms m-line
dystrophin: links thin filaments (actin) to sarcolemma
titin: stabilizes position of myosin, allowsing stretching and returning to shape
thin vs thick filament
thick: myosin
thin: actin
I band
only contains thin filaments (actin)
M line
middle of sarcomere
A band
entire length of thick filament (myosin)
H zone
one actin to another, only containing thick filaments
Wolff’s Law
bone will adapt to load under which it’s placed bcs more muscle = more weight = more bone
bone will resemble function
bone is resorbed from places it’s not needed
bone remodelling steps
- osteoclasts resorb old bone
- osteoblasts lay down new bone
estrogen induces osteoclast apoptosis
- menopause causes osteoclasts to live longer
what does EMG give info on
- what muscles are active/prime mover
- show rigidity i.e. parkinsons
- how much tension generated
- timing of muscle activation (when they are recruited)
- fatigue state i.e. when muscle gets tired, force production down, electrical activity dec
