<P> The sarcoplasmic reticulum ( SR ) , from the Greek σάρξ sarx ( `` flesh '' ) , is smooth ER found in myocytes . The only structural difference between this organelle and the smooth endoplasmic reticulum is the medley of proteins they have , both bound to their membranes and drifting within the confines of their lumens . This fundamental difference is indicative of their functions : The endoplasmic reticulum synthesizes molecules , while the sarcoplasmic reticulum stores calcium ions and pumps them out into the sarcoplasm when the muscle fiber is stimulated . After their release from the sarcoplasmic reticulum , calcium ions interact with contractile proteins that utilize ATP to shorten the muscle fiber . The sarcoplasmic reticulum plays a major role in excitation - contraction coupling . </P>
<P> The sarcoplasmic reticulum ( SR ) , from the Greek σάρξ sarx ( `` flesh '' ) , is smooth ER found in myocytes . The only structural difference between this organelle and the smooth endoplasmic reticulum is the medley of proteins they have , both bound to their membranes and drifting within the confines of their lumens . This fundamental difference is indicative of their functions : The endoplasmic reticulum synthesizes molecules , while the sarcoplasmic reticulum stores calcium ions and pumps them out into the sarcoplasm when the muscle fiber is stimulated . After their release from the sarcoplasmic reticulum , calcium ions interact with contractile proteins that utilize ATP to shorten the muscle fiber . The sarcoplasmic reticulum plays a major role in excitation - contraction coupling . </P>
what is the function of the smooth endoplasmic reticulum quizlet
what is the function of the smooth endoplasmic reticulum quizlet
The endoplasmic reticulum synthesizes molecules
The endoplasmic reticulum synthesizes molecules