The Sarcoplasmic Reticulum

Question

The sarcoplasmic reticulum
A) stores ACh.
B) is located within the neuromuscular junction.
C) envelops the sarcomere-containing myofibrils.
D) is a contractile protein.

Accepted Answer

The sarcoplasmic reticulum is a specialized type of smooth endoplasmic reticulum that surrounds each myofibril (bundle of sarcomeres) in a muscle cell. It stores and releases calcium ions, which are necessary for muscle contraction. It does not store ACh, is not located within the neuromuscular junction, and is not a contractile protein.