Myosin binds to actin, then bends. What is ATP needed for next? A. to pump the Ca++ “keys” back into the sarcoplasmic reticulum B. to replace the strap and cover the binding sites C. to give feedback to the neuron that contraction occurred D. to un-bind myosin from actin and re-set for another powerstroke.

Myosin binds to actin, then bends. What is ATP needed for next? A. to pump the Ca++ “keys” back into the sarcoplasmic reticulum B. to replace the strap and cover the binding sites C. to give feedback to the neuron that contraction occurred D. to un-bind myosin from actin and re-set for another powerstroke.

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter8: Muscle Physiology

Section: Chapter Questions

Problem 11RE

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Similar questions

After death, a person no longer makes ATP, so calcium stored in the sarcoplasmic reticulum diffuses down its concentration gradient into the muscle cytoplasm. This result is rigor mortis----an unbreakable state of muscle contraction that stiffens the body for a few days until muscles begin to decay. Explain why this contraction occurs.
The release of calcium ions initiates muscle contractions. Watch this video (http://openstaxcollege.org/l/calciumrole) to learn more about the role of calcium. (a) What are â€œT-tubulesâ€� and what is their role? (b) Please also describe how actin-binding sites are made available for cross-bridging with myosin heads during contraction.
The _____ is the basic unit of muscle contraction. a. myofibril b. sarcomere c. muscle fiber d. myosin filament
Every skeletal muscle fiber is supplied by a motor neuron at the NMJ. Watch this video (http://openstaxcollege.org/l/skelmuscfiber) to learn more about what happens at the neuromuscular junction. (a) What is the definition of a motor unit? (b) What is the structural and functional difference between a large motor unit and a small motor unit? Can you give an example of each? (c) Why is the neurotransmitter acetylcholine degraded after binding to its receptor?
Figure 38.37 Which of the following statements about muscle contraction is true? The power stroke occurs when ATP is hydrolyzed to ADP and phosphate. The power stroke occurs when ADP and phosphate dissociate from the myosin head. The power stroke occurs when ADP and phosphate dissociate from the actin active site. The power stroke occurs when Ca2+ binds the calcium head.
Rigor mortis occurs following death because a. tropomyosin remains over the myosin binding sites of actin. b. myosin heads attach to actin and are not released due to lack of ATP. c. the myosin becomes misshapen. d. all of the Ca2+ remains within the sarcoplasmic reticulum.
What might happen if skeletal muscle lacked tropomyosin? A. The striation pattern would disappear. B. Ca2+ levels in the muscle would decrease. C. Actin and myosin would not be able to form cross-bridges. D. Acetylcholine would not be released into the synaptic cleft. E. Myosin and actin would form cross-bridges whenever ATP is available.
What does ATP binding to myosin head triggers? a. Its association with microtubules b. Its dissociation from actin microfilament c. Conformational change and rotation of myosin head d. Its association with actin microfilament
During the contraction of a vertebrate skeletal muscle fiber,calcium ions(A) break cross-bridges as a cofactor in hydrolysis of ATP.(B) bind with troponin, changing its shape so that the myosinbinding sites on actin are exposed.(C) transmit action potentials from the motor neuron to themuscle fiber.(D) spread action potentials through the T tubules.
The function of ATP during muscle contraction is toa. cause an allosteric change in myosin so it detaches from actin.b. provide the energy necessary for the movement of the cross-bridge.c. expose the myosin-binding sites on the thin filaments.d. do all of the above.e. do a and b only.
According to the sliding filament model, when muscles contract,a. sarcomeres shorten.b. myosin heads break down ATP.c. actin slides past myosin.d. the H zone disappears.e. All of these are correct
What is released when myosin heads attach to actin filaments A. Phosphate B. ATP C. ADP D. Tropomyosin