Narrow T-tubules permit the conduction of electrical impulses. The SR functions to regulate intracellular levels of calcium. Two terminal cisternae (where enlarged SR connects to the T-tubule) and one T-tubule comprise a triad—a “threesome” of membranes, with those of SR on two sides and the T-tubule sandwiched between them.
Cut Rita Zahara
“The T-tubule ,” Open Educational Resource (OER) - UNM, accessed February 21, 2020, http://oer.unm.ac.id/items/show/1124.