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
The release of ADP+Pi causes what?
the myosin head to pivot toward the M line.
The action of the myosin head pivoting toward the M line is known as the ________ __________.
Power stroke.
The power stroke occurs when the bound _____ and ___ are released.
ADP and Pi
After the power stroke, what happens?
The myosin remains attached to the actin until a molecule of ATP binds.
When ____ binds, the link between the _____ head and the myosin binding site on _____ is _______.
ATP, myosin, actin, broken
Once the link is broken between myosin and actin, what does this mean?
This means that the binding site is now free/exposed and able to form another cross bridge.
Name the last stage in muscle contraction.
Myosin Reactivation
When does myosin reactivation occur?
When the free myosin head splits ATP into ADP and Pi.
The energy released when ATP splits into ADP and Pi is used to do what?
Its used to recock the myosin head- this allows the cycle to start again :)
What is essential for contraction?
ATP
What enzyme is located in the myosin head?
myofibrillar ATPase (mATPase)
ADP»_space;»> ATP happens in the ______ stage.
resynthesis
ATP»»»»>ADP happens during _____.
contraction
What is ATP also required for?
Its required to pump calcium back into the sarcoplasmic reticulum during relaxation.
What is the main way the body produces ATP?
Aerobic Respiration
Anaerobic respiration produces ____ ATP.
2
Aerobic respiration produces ________ ATP and is better for _____ contractions.
38, sustained
