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6:01
7:18 6:01Which of the following statements accurately describes the role of ATP in a muscle contraction?
a. ATP is directly responsible for the power stroke.
b. ATP moves troponin and tropomyosin away from actin.
c. ATP breaks the actin/myosin attachment and 'cocks' the myosin head.
d. ATP causes the myofilaments to shorten.
Paola is a 3-year-old girl with a disease that reduces the ability of her mitochondria to generate ATP. Explain the specific effects of this disease on the ability of Paola's muscles to function properly. What other tissues and organs are likely to be especially affected by her disease, and why?
Mr. Nasheed has cerebral palsy and suffers severe skeletal muscle spasms as a result of his condition. He is prescribed the drug dantrolene, which prevents the release of Ca2+ from the SR. Explain how this will treat his muscle spasms.
Order the following events of excitation and excitation-contraction coupling. Put 1 by the first event, 2 by the second, and so on.
____ The motor end plate generates an end-plate potential.
____ The action potential spreads along the T-tubules, SR Ca2+ channels are pulled open, and Ca2+ floods the cytosol.
____ Acetylcholine binds to receptors on the motor end plate, and ligand-gated ion channels open.
____ Ca2+ bind troponin, which allows tropomyosin to move away from the actin active site, initiating a contraction cycle.
____ The action potential propagates through the sarcolemma and dives deeply into the cell along the T-tubules.
Some athletes will consume only protein for several days before a competition, which reduces the amount of glycogen in both the muscle fibers and the liver. What effect would this have on their ability to perform activities that require short, powerful bursts of activity? How would it affect their ability to perform endurance activities?
What is the basic mechanism of contraction at the level of myofilaments?
