Muscle Physiology Flashcards
muscle cell
muscle fiber
cell membrane
sarcolemma
cytoplasm
sarcoplasm
modified endoplasmic reticulum (ER)
sarcoplasmic reticulum
neuromuscular junction
when a motor neuron stimulates a muscle cell to contract by causing a chemical synapse between the nerve terminal and motor end plate
sliding filament theory
contraction of a muscle when the thin filament slides past the thick filament; sarcomere shortens and the thin and thick filaments overlap
actin
major component of the thin filament; each actin subunit has a specific binding site for the myosin cross bridge
tropomyosin
regulatory protein of the thin filament entwined around actin and covers myosin binding sites
troponin
attached to and spaced periodically on tropomyosin strand; exposes the binding sites on actin
end-plate potential (EEP)
caused by depolarization of the muscle fiber membrane
muscle twitch
a single contraction-relaxation cycle of the muscle
single twitch
muscle relaxes completely between stimuli
summation
muscle does not relax completely as stimuli are close together
summation leading to tetanus
muscle only relaxes slightly between stimuli that are very close together
sources of glucose
enters the muscle cell directly from the blood or is produced by hydrolysis of glycogen stored in the muscle cell
sources of oxygen
enters the muscle cell directly from the blood or is stored in myoglobin
isometric contraction
muscle exerts force without changing length; plank holds and wall sits
isotonic/dynamic contraction
muscle exerts force by changing length
concentric contraction
muscle shortens during force production; bicep curls and sit-ups
eccentric contractions
muscle lengthens during force production; squats and triceps extensions
muscle spindle
changes muscle length; contains actin and myosin for contraction
golgi tendon organ (GTO)
monitors tension development, prevents damage during excessive force, stimulation results in reflex relaxation
