Answer
In striated muscle contraction the source of calcium ions is the sarcoplasmic recticulum. In smooth muscle contraction the Ca++ ions derive from extracellular fluid through gated channels in the sarcolemma as well as from Ca++ stored in the sarcoplasmic recticulum.
Work Step by Step
The protein that binds Ca++ ions in skeletal muscle is troponin. However, smooth muscle has no troponin, and calcium binding is done by the protein calmodulin.
