4. Frog Muscle Physiology
basic muscle twitch
a single contraction of skeletal muscle, the response of skeletal muscle to stimulation
threshold stimuli
a stimuli that is just strong enough to change the membrane from resting potential to threshold
maximal stimuli
stimuli that are strong enough to produce action potentials in all motor units of a particular muscle
basic muscle twitch (events that cause)
1) ACh molecules bind to NICOTINIC RECEPTORS 2) Ion Channels Open 3) Sodium Ions Flow In → (Contraction Cycle Initiated)
intensity
1/3 Basic muscle twitch: Events -VOLTAGE CHANGE Increasing Stimuli = ↑Excited Motor Units, ↑Contraction Strength
Frequency
2/3 Basic muscle twitch: Events -PULSES/SECOND ↑ _____________ = ↑ Contraction Strength
Muscle Tissue Condition
3/3 Basic muscle twitch: Events -TEMPERATURE -O2 Level -ION CONCENTRATION
incomplete tetanus
5-10 shocks/second
twitch
A single electrical shock results in a _________.
action potential
A twitch produces an _________ __________ which leads to contraction.
contraction
A twitch produces an action potential which leads to _____________________.
increase
Increasing FREQUENCY of stimulus will _______________ MOTOR UNIT RECRUITMENT
Number of motor units reruited
Increasing VOLTAGE increases the __________________________.
force
Increasing the # of MOTOR UNITS firing will increase muscle _____________.
complete tetanus
Shows fatigue after 60 shocks/second
subthreshold stimuli
Stimuli below the minimum strength needed to trigger any of the muscle fibers to reach threshold and undergo an action potential
supramaximal stimuli
This is the strongest contraction and is due to longer period of time that all motor units respond
summation
When a second muscle twitch piggy backs on the first, it's called _______________, which leads to a STRONGER contraction.