Which of the following statements about the Ca2+ release channels in the sarcoplasmic reticulum is false? a.They are also called ryanodine receptors. b.They are one-tenth the size of the voltage-gated Ca 2+channels. c.They are opened by Ca2+release channels in the transverse tubules. d.They permit Ca 2+ to diffuse into the sarcoplasm from the sarcoplasmic reticulum.

Which of the following statements about the Ca2+ release channels in the sarcoplasmic reticulum is false? a.They are also called ryanodine receptors. b.They are one-tenth the size of the voltage-gated Ca 2+channels. c.They are opened by Ca2+release channels in the transverse tubules. d.They permit Ca 2+ to diffuse into the sarcoplasm from the sarcoplasmic reticulum.

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

See similar textbooks

Similar questions

Calmodulin is found in smooth muscle cells and performs a similar function to troponin in striated muscle fibers. However, calmodulin not only gets activated by Ca2+ but also slows the release of Ca2+ from the sarcoplasmic reticulum. How might this difference relate to the different kinds of contractions smooth muscles do in comparison to striated muscles?
What event causes a troponin-tropomyosin complex to regain its original shape in muscle relaxation? a. stimulation of ACh receptors b. diffusion of Na+ back into transverse tubules c. return of Ca2+ into the sarcoplasmic reticulum d. breaking of the bond with tropomyosin
If a muscle cell had very short T-tubules, how much tension would the muscle fiber create, relative to a normal muscle fiber? Assume sarcoplasmic reticulum can still react to activity at the neuromuscular junction. a)Less tension would be created. b) No difference in tension creation. c) More tension would be created. d) No tension would be created.
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.
Which of the following statements best describes the sliding filament mechanism of muscle contraction? a. Actin and myosin filaments do not shorten, but rather, slide past each other. b. Actin and myosin filaments shorten and slide past each other. c. As they slide past each other, actin filaments shorten, but myosin filaments do not shorten. d. As they slide past each other, myosin filaments shorten, but actin filaments do not shorten.
Muscle relaxation occurs when ________. a. calcium ions are actively transported out of the sarcoplasmic reticulum b. calcium ions diffuse out of the sarcoplasmic reticulum c. calcium ions are actively transported into the sarcoplasmic reticulum d. calcium ions diffuse into the sarcoplasmic reticulum
With regard to muscle contraction, which of the following is an INCORRECT statement with regard to the interactions of filaments that occur in the sarcomere? A. When muscles are relaxed tropomyosin blocks binding sites on actin subunits, which keeps cross-bridges from forming. B. The myosin heads conduct a power stroke motion to slide when bound to actin, to move the "thin" filaments towards the center of the sarcomere. C. During contraction, actin subunits are removed from the ends of the "thin" filaments to shorten actin polymers, thus reducing the length of the sarcomere. D. "Thick" filaments are anchored at the M-line, while "thin" filaments are anchored at the Z-line. E. Numerous myosin heads engage with the actin filaments simultaneously, such that there is no back-slipping during the contraction process.
When sarcomeres contract during muscle contraction, which of the following occurs? A. The myosin filaments lengthen. B. The myosin filaments "walk" along the actin microfilaments. C. The myosin filaments shorten. D. The actin filaments shorten.
When a muscle fiber is stretched from 60% of its optimal length to Lo, what change or changes are happening on the cellular level (MULTIPLE SELECT)? A. Increased calcium release from the SR B. Increased firing of action potentials from the alpha motor neuron C. Increased rate of myosin ATPase activity D. Increased number of actin-myosin bridges E. Increased stretch on titin, producing more passive force
if, in a laboratory, a skeletal muscle cell receives a single stimulus to contract, it produces a single muscle twitch. If we quickly fire another stimulus for the muscle to contract, prior to the muscle fully relaxing, then we have a condition of: A. seizure B. none of the above C. complete tetanus D. temporal summation E. relaxation The _________________ phase of the Sliding Filament Model of Contraction occurs when myosin and actin separate from one another. A. cocking of the myosin head B. cross bridge detachment C. cross bridge formation D. action potential E. calcium release During contraction, the bulk of calcium comes from the?
In muscle cells, magnesium ions compete with calcium ions for binding sites on troponin molecules. If a person has too high a concentration of magnesium ions in the blood, magnesium ions can prevent calcium ions from binding troponin. A) What effect would this have on muscle contraction (strengthen, weaken, or no effect)? B) Use your knowledge of how muscle fibers contract to explain your answer in part A.
If you introduced a chemical into a muscle fiber that blocked the voltage-gated calcium channels in the sarcoplasmic reticulum, what effect if any, would this have on the contraction of that muscle fiber?