sliding filament mechanism steps Flashcards
(1) nerve impulses arrive at
the axon terminal
once the impulses arrives at the axon terminal
ACH is released and diffused across the synapse to the sarcolemma
(2) ACH bonds with
ACH receptors
ACH bond makes
sarcolemma more permeable to sodium ions to rush into the cell
(3) sarcolemma
depolarizes
once the sarcolemma depolarizes
T Tubules bring reversal of charge to inferior of muscle cells
(4) depolarization stimulates release of
Ca2 ions from sarcoplasmic reticulum
once depolarization stimulates the release of Ca2 ions
Ca2 ions bond to the troponin-tropomyosin complex
troponin-tropomyosin complex
shifts Ca2 ions away from actin filaments
(5) myosin splits ATP to
release its energy
(also 5) bridges on the myosin attach to actin filaments and
pull them toward the center of the sarcomere
the pulling towards the center of the sarcomere makes
the sarcomere shorter
(6) all of sarcomeres in a muscle fiber
shorten and the entire muscle fiber contracts
step 7
sarcolemma repolarizes
(8) cholinesterase in sarcolemma
inactivates ACH
(9) subsequent nerve impulses will
(9) subsequent nerve impulses will
prolong contractions (more ACH released)
(10) when there are no more nerve impulses
the muscle fiber will relax and return to original length
steps 1-8 (twitch)
describe a single muscle fiber contraction in a response to a single nerve impulse
because all of this takes place in less than a second
useful movements would not be possible if muscle fibers relaxed immediately after contracting
tetanus
sustained contractions
tetanus/sustained contractions
nerve impulses arrive in a continuous stream and produced sustained contraction
when in tetanus
muscle fibers remain contracted and are capable of effective movement
