Question 9

(Multiple Choice)

What is occurring during this period of a muscle twitch contraction? What is occurring during this period of a muscle twitch contraction?   A) The muscle action potential sweeps along the sarcolemma and calcium ions are released from the sarcoplasmic reticulum. B) Crossbridge attachments form, and repetitive power strokes occur. C) The level of Ca<sup>2+</sup> in the sarcoplasm decreases, because it is being actively transported back into the sarcoplasmic reticulum and bound to calsequestrin. D) The muscle fiber relaxes as myosin heads detach from the actin filaments. E) Acetylcholinesterase is preventing the ligand gated channels at the motor end plate from binding to ACh.


A) The muscle action potential sweeps along the sarcolemma and calcium ions are released from the sarcoplasmic reticulum.
B) Crossbridge attachments form, and repetitive power strokes occur.
C) The level of Ca2+ in the sarcoplasm decreases, because it is being actively transported back into the sarcoplasmic reticulum and bound to calsequestrin.
D) The muscle fiber relaxes as myosin heads detach from the actin filaments.
E) Acetylcholinesterase is preventing the ligand gated channels at the motor end plate from binding to ACh.

Answer