The three main components of a triad are: 1. T-tubules: Invaginations of the sarcolemma that penetrate into the interior of the muscle fiber, allowing the action potential to reach deep within the cell. 2. Terminal cisternae: Enlarged areas of the sarcoplasmic reticulum that flank each T-tubule and store calcium ions. 3. Sarcoplasmic reticulum: A specialized form of the endoplasmic reticulum in muscle cells, responsible for the storage and regulation of calcium ions.
