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BMSC 207 Muscle 1,2 and 3 Test with Questions Solved 100% Correctates the myosin head to the cocked position. ATP is broken down to ADP and inorganic phosphate (Pi) resulting in the myosin head pivoting around hi$13.24
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BMSC 207 Muscle 1,2 and 3 Test with Questions Solved 100% Correctates the myosin head to the cocked position. ATP is broken down to ADP and inorganic phosphate (Pi) resulting in the myosin head pivoting around hi
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Course
BMSC 207
Institution
BMSC 207
BMSC 207 Muscle 1,2 and 3 Test with
Questions Solved 100% Correctates the myosin head to the
cocked position. ATP is broken down to ADP and inorganic phosphate (Pi)
resulting in the myosin head pivoting around hi
BMSC 207 Muscle 1,2 and 3 Test with
Questions Solved 100% Correct
cross bridge cycle - Answer Ca bound to troponin and nothing bound to myosin head.
process of cross bridge cycle - Answer 1. ATP binds to myosin: myosin releases actin,
ATP binds to the head of myosin heavy chain reducing affinity of myosin for actin.
2. Myosin hydrolysis ATP: energy from ATP rotates the myosin head to the
cocked position. ATP is broken down to ADP and inorganic phosphate (Pi)
resulting in the myosin head pivoting around hinge into cocked state which binds
to a new actin molecule.
- Myosin is present in the above steps.
3. Power stroke: beings when Pi is released from myosin head and strengthens
bond b/w actin and myosin. Power stroke is triggered and conformational change
where myosin head returns to its un-cocked state.
4. ADP release: Myosin releases ADP to the end of the power stroke causing myosin to
remain bound to actin until ATP initiates the cycle again.
termination of contraction - Answer Once AP has subsided, Ca2+ must be removed so
that the myosin binding site on actin can be covered by tropomyosin.
form of termination of contraction - Answer 1. Ca2+ can be removed into the
extracellular space by the Na- Ca exchanger or by the Ca2+ pump which uses ATP.
,- This would deplete the cell of any Ca2+, leaving SR empty so it is a MINOR ROLE.
2. Ca can be reuptaken into the SR by the Ca2+ - ATPase (SERCA)- type CA2+ pump
inhibited by high Ca2+ in the SR.
- Calsequestrin and caleretriculm max Ca2+ uptake by SR.
rigor mortis - Answer - is the development of rigid muscle several hours after
death where Ca2+ leaks into the sarcoplasm and binds to troponin.
effects of rigor mortis - Answer - ATP production stops so Ca2+ can't be removed
and the myosin head is not released from actin.
- Remains in latched cross bridge formation until muscles begin to deteriorate.
Timing of E-C coupling - Answer - Synaptic release is a slight delay b/w motor neuron AP
and muscle fibre AP.
- Latent period is the delay b/w muscle fibre AP and contraction time when Ca2+
is released and binds to troponin.
atp is needed for - Answer - Myosin ATPase (contraction)
- Ca2+ ATPase: SERCA (relaxation)
- Na/K ATPase (after AP in muscle fibre)
atp sources - Answer - Free intracellular ATP (few seconds)
- ATP stored as phosphocreatine (10 seconds)
- Glycolysis (anaerobic metabolism) which is rapid but inefficient, 1 glucose produces 2
ATP.
- Aerobic (oxidative) metabolism if O2 and mitochondria is present in muscle fibre.
, glycogenesis - Answer A large amt of glucose is stored in muscle cells in the form of
glycogen
Glycogenolysis - Answer When ATP is needed glycogen is converted back to glucose
anaerobic metabolism (glycolysis) - Answer If there is no O2, this happens and
pyruvate is broken down to lactate.
aerobic metabolism (oxidative) - Answer - If O2 and mitochondria is present, then this
will happen and pyruvate enter the citric acid cycle producing 2 more molecules of
ATP and high energy e-.
- E- and H+ combine with O2 in e- transport chain to produce 26-28 molecules of ATP
in mitochondria.
muscle fatigue - Answer - is a decrease in muscle tension as a result of
previous contractible activity that is reversible.
- There is central and peripheral fatigue.
central fatigue - Answer is the feeling of tiredness and a desire to cease activity
(physiological cell fatigue occurs in the brain). Low pH from acid production during
ATP hydrolysis can influence the sensation of fatigue perceived by the brain.
peripheral fatigue - Answer can occur anywhere in the body where the ACh synthesis
can't keep up with neuron firing and it decreases the neurotransmitter release, AChR
activation and muscle fails.
failed excitation- contraction coupling - Answer - occurring at the T- tubules where
there are repeated AP firing, K+ builds up in the T- tubules (extracellular space) changing
the threshold for AP's in the muscle fiber. This can cause a depolarization of the
membrane and there could be a failure of propagation.
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