Read instructions carefully Muscle contraction is triggered…

Read instructions carefully Muscle contraction is triggered by an [a] (two words) traveling from [b], which is the muscle cell membrane, to the [c] regions, which consist of two large sacs of the [d] reticulum and a portion of a structure called [e] (do not abbreviate) tubules.  This activates the release of [f] from the SR and initiates muscle contraction.

Read instructions carefully Calcium released from specific r…

Read instructions carefully Calcium released from specific regions of the sarcoplasmic reticulum called [a] (two words, do not abbreviate) binds to [b] (name of a particular protein), which changes troponin conformation and causes [c] to shift and expose [d]-binding sites on actin filaments so that they can bind to the thick filaments.