Muscular System Flashcards
Acetylcholinesterase
the enzyme that breaks down acetylcholine in the synaptic cleft
excitation-contraction coupling
events that link the action potentials on the sarcolemma to activation of the myofilaments, thereby preparing them to contract
cross bridge formation
high-energy myosin head attaches to actin thin filament active site
recovery position is the combination of what?
ADP + phosphate
A power stroke involves:
a myosin head pulling a thin filament toward the center of the sarcomere.
recovery involves
breakdown of ATP to ADP
relaxation of muscle
Calcium concentration rapidly decreases when muscle stimulation ceases, calcium is actively pumped back into sarcoplasmic reticulum, tropomyosin returns to resting position covering the actin binding sites
phases of muscle twitch
lag, contraction, relaxation
submaximal muscle stimulus
no more units available
maximal muscle stimulus
full motor unit recruitment
difference of muscle threshold and nervous threshold
muscle: motor unit recruitment
nervous: effect on relative refractory period
incomplete tetanus
muscle fibers partially relax between contraction
complete tetanus
no relaxation between contractions; muscle stays contracted
multiple wave summation
frequency of action potentials increases as contraction frequency increases
Treppe
Phenomenon in which each successive twitch contracts more forcefully than the previous one; muscles not primed or potentiated
types of muscle contractions
isometric, isotonic, muscle tone
isometric muscle contraction
change in length but tension constant
-eccentric
-concentric
muscle tone
constant tension by muscles for long periods of time
isokinetic contraction
same movement; concentric only, no eccentric
psychological muscle fatigue
emotional state; no physical reason to stop
muscular fatigue
results from ATP depletion
synaptic muscle fatigue
occurs in NMJ due to lack of acetylcholine
