Question: Part C – How an action potential affects Ca2+ movement in a muscle cell The sarcoplasmic reticulu…

Part C – How an action potential affects Ca2+ movement in a
muscle cell The sarcoplasmic reticulum is a specialized form of ER
that surrounds each myofibril. The sarcoplasmic reticulum functions
to control cytosolic Ca2+ levels in the muscle cell. Changes in
cytosolic Ca2+ concentrations couple action potentials to muscle
contraction. The concentration of Ca2+ ions in the sarcoplasmic
reticulum is typically much higher than the Ca2+ concentration in
the cytosol. This concentration gradient is key to the movement of
Ca2+ in the muscle cell in response to an action potential. The
cycle diagram below shows the sequence of events that affect Ca2+
levels in a muscle cell, beginning with the propagation of an
action potential down a T tubule (top of the diagram). Drag the
labels to their appropriate locations on the cycle diagram below.
Note that SR stands for sarcoplasmic reticulum.