Sliding Filament Theory Flashcards
What is the sliding filament theory?
explains muscle contraction based on how muscle fibers (actin and myosin) slide against each other to generate tension in the overall muscle
What is the first step to the theory?
muscle contraction starts in the brain, a signal is sent to the motor neuron
The motor unit consists of what?
muscle fibers and a motor neuron
Vesicles within the motor neuron contain what?
the neurotransmitter, acetylcholine
What happens when acetylcholine reaches the receptors?
the impulse travels down the sarcolemma membrane
What is the gap between the neuron and muscle fibers called?
synapse
What is second step of the theory after a signal is sent to the motor neuron?
the impulse travels into the transverse tubules where it causes calcium to be released from the sarcoplasmic reticulum
What substance causes the actin to change shape?
calcium
What is the third step of the theory after calcium is released?
calcium binds to the actin and causes it to change shape so it can interact with myosin
What is the fourth step of the theory after actin interacts with myosin?
the change in shape allows myosin heads to form cross-bridges between actin and myosin
What is the fifth step of the theory after cross-bridges are formed?
energy from ATP is used to create a “power stroke” between the two filaments. the actin slides inward and shortens, or contracts, the whole muscles
What substance provides energy for muscle contraction?
ATP
Where is calcium released from?
transverse tubules
What are the two filaments found in muscles?
actin and myosin
What are the steps of the theory?
- a signal travels down the motor neuron
- calcium is released from the sarcoplasm
- actin changes shape
- cross-bridges form
- ATP creates power stroke, shortening actin filament
