Exam 3 Flashcards
what makes up a motor unit
nerve (motor neuron aka efferent)
muscle fibers
what are the filaments within the sarcomere
actin and myosin
small contractile units
sarcomeres
sliding filament theory
-action potential causes myosin heads to flex and create cross bridges with actin
-myosin pulls actin toward sarcomere center
-H-band becomes smaller
-Z discs move toward center
-changes in sarcomere length
I-bands
contains actin
A-band
contains myosin
action potential sequence
- action potential is released to trigger nerve response at motor end plate
- release of Ach at motor end plate initiates muscles response
- Ca+2 ions released from SR
- Ca+2 ions bind to troponin to slide tropomyosin away from actin binding sites
- extended myosin heads attach to actin’s binding sites, creating cross-bridges
- myosin contact with actin causes hydrolysis of ATP to ADP and phosphate, producing energy
- ADP releases from myosin heads creating “power stroke” as myosin heads move back to uncocked position while attached to actin
- new ATP attaches to myosin, detaching myosin from actin
- Ca+2 releases from troponin and re-enters SR
- tropomyosin covers actin binding sites
- sarcomeres returns to proactivity conditions
4 whole muscle functions
produce movement
maintain posture
stabilize joints
generate body heat
characteristics of type 1 muscle fiber
slow
small
red
greatest resistance to fatigue
lots of mitochondria
high oxidative capacity
oxidative system
endurance/aerobic activity
characteristics of type 2A muscle fibers
fast
larger
white
moderate to fatigue
high oxidative capacity
ATP-PC system
high-intensity activity less than 2min
characteristics of type 2B muscle fibers
fastest
largest
white
fatigue easily
minimal mitochondria
glycolytic system
max-intensity bursts, less than 30 sec
muscle strength
max force a muscle or muscle group can exert
determining factors: genetics, gender, exercise, neural recruitment, lifestyle, muscle fiber type
power
strength applied over a distance for a specific time (P = Fxd/T)
components of power
strength
speed
coordination
movement efficiency
timing
muscle endurance
ability to perform repeated contractions against less than max load
determining factors of muscle endurance
energy system used (type 1 recruited first then type 2 if enough stimulation)
quantity of force resisted
T/F endurance is inversely proportional to force intensity
true
strength is developed through
low reps with high resistance
endurance is developed through
high reps with low resistance
rest for strength
longer rests between sets and reps
rest for endurance
shorter rest periods
sources of muscle fatigue
neural system (out of Ach to use)
energy system (out of ATP)
sarcoplasmic reticulum (runs out of Ca+2)
T/F according to the sliding filament theory, action potential causes actin heads to flex and create cross-bridges with myosin filaments
false
what fiber type uses oxidative energy system
type 1 muscle fibers