Sliding Filament Theory Flashcards
Epimysium
Surrounds entire muscle and blends into intramuscular tissue sheaths to form tendons
Perimysium
Surrounds a bundle of fiber called fasciculus
Endomysium
Wraps each muscle fibers and separates it from neighboring fibers
Sarcolemma
Surrounds each muscle fiber and encloses fiber’s cellular contents
Sequence of Events in Muscle Action: Step One
Action potential causes terminal axon to release ACh, which diffuses across synaptic cleft and attaches to receptors on sarcolemma
Sequence of Events in Muscle Action: Step Two
Action potential depolarizes transverse tubules at the sarcomere’s A-I junction
Sequence of Events in Muscle Action: Step Three
Depolarization of T-tubule system causes Ca(2+) release from lateral sacs of SR
Sequence of Events in Muscle Action: Step Four
Ca(2+) binds to troponin-tropomyosin in actin filaments
Sequence of Events in Muscle Action: Step Five
Actin combines with myosin-ATP, this activates myosin ATPase,which splits ATP
The reaction’s energy produces myosin crossbridge movement and creates tension
Sequence of Events in Muscle Action: Step Six
ATP binds to myosin crossbridge which breaks actin- myosin bond, allowing actin dissociation with the crossbridge
Sequence of Events in Muscle Action: Step Seven
Crossbridge activation continues when Ca(2+) concentration remains high enough to inhibit troponin-tropomyosin system
Sequence of Events in Muscle Action: Step Eight
active transport moves Ca(2+) back to lateral sacs (concentration decreases) after muscle stimulation ceases
*requires ATP hydrolysis
Sequence of Events in Muscle Action: Step Nine
Ca(2+) removal restores inhibitory action of troposin- tropomyosin
In presence of ATP, actin and myosin remain in a relaxed state (dissociated)
Stretch reflex consists of three components
- Muscle spindle: responds to stretch
- Afferent nerve fiber carries sensory impulse from spindle to SC
- Efferent spinal cord motor neuron activates stretched muscle fiber’s
