Skeletal Muscle Contraction. Flashcards
The process of contraction involves _____ _______ of sarcolemma.
neural stimulation
What coupling does neural stimulation cause?
causes “excitation-contraction” coupling.
Muscle fibre contraction is caused by the ______ of thick and thin _______.
interaction, filaments
Force is produced during muscle contraction, what can this also be called?
Tension Production
What is a motor unit?
A motor neuron and all the muscle cells it stimulates.
When a motor neuron reaches the muscle cell, this is called a ______ _______.
neuromuscular junction
Motor neurons reach the spinal ____ that then connects to part of the spinal _____.
nerve, cord
Synaptic ____ containing _______ will pass from the _____ _______ into the muscle cell.
vesicles, acetylcholine, axon terminal.
What is the synaptic cleft?
The space between neuron and in this case the muscle cell, at a nerve synapse.
Muscle contraction is stimulated by what stimulation?
neural stimulation
What does neural stimulation induce?
Calcium Ion release.
Where is calcium released from?
The sarcoplasmic reticulum of the myofibril.
Calcium binds to _____ more specifically _____.
Actin, troponin
When calcium binds to actin, how does this initiate contraction?
By exposing myosin binding sites on each actin molecule.
Where does muscle contraction occur?
In skeletal muscles
What does the Contractile Cycle/ Muscle Contraction begin with?
it begins with the arrival of calcium ions within the zone of overlap.
Calcium ions bind to ______, this _______the _____between actin and the troponin-tropomyosin.
troponin, weakens, bond.
Once the bond is weakened, this then causes the troponin to change ______, rolling the ________.
position, tropomyosin
When the tropomyosin is rolled what does this expose?
This exposes the myosin binding sites on each actin molecule.
Once the myosin sites on each actin molecule are exposed, what does this allow?
This allows interaction with the energized myosin heads.
What is the 3rd stage in Muscle Contraction (after active site exposure)?
Cross-Bridge Formation
Once the active sites are exposed the _____ myosin heads _____ and bind to the binding/active sites on _____. This forms a _____ _______.
energized, extend, actin, cross-bridge
After a cross bridge is formed what happens?
The myosin head pivots toward the M line.
What happens to the energy that was stored in the resting state after cross-bridge formation?
it is released in the form ADP+Pi
