actin filaments
sarcomere
biceps muscle
myosin filaments
myofibril
bundle of muscle fibers
muscle fiber
During a muscle contraction, which of the following shorten?
the sarcomere
the actin filaments
the myosin filaments
All of the above.
Muscle contraction occurs as sarcomeres shorten in a four-step process. At the start of the process, actin and myosin filaments are linked together, and the sarcomere is relaxed. Which of the following four steps occurs first?
reach
pull back
detach
reattach
During the “detach” step, has the sarcomere changed length?
Yes. It has contracted.
No. It remains relaxed.
Which of the following occurs after the “detach” step of sarcomere shortening?
reattach
pull back
reach
During the “reach” step, has the sarcomere changed length?
Yes. It has contracted.
No. It remains relaxed.
Which of the following occurs after the “reach” step of sarcomere shortening?
pull back
reattach
During the “reattach” step, has the sarcomere changed length?
Yes. It has contracted.
No. It remains relaxed.
During the “pull back” step, has the sarcomere changed length?
Yes. It has contracted.
No. It remains relaxed.
True or False: Neither the actin nor myosin filaments changed length as the sarcomere went from a relaxed to a contracted state.
TRUE
FALSE
Muscle Contraction Summary