calcium
Calcium
Calcium
terminal cisternae of the sarcoplasmic reticulum
The part of the sarcoplasmic reticulum where calcium ions are stored is called the terminal cisternae. These structures are found at the ends of the sarcoplasmic reticulum and play a key role in releasing calcium ions into the muscle cell during muscle contraction.
in the terminal cisternae
In skeletal muscle, a triad is formed when a T-Tubule is flanked on either side by the calcium containing Terminal Cisternae of the Sarcoplasmic Reticulum, at the level of the Z-line. The intimate association of these three membranous sturctures (Terminal Cisternae---T-Tubule---Terminal Cisternae) for a Triad. This differs from a diad (or Dyad), in cardiac muscle where the T-Tubule is only intimately associated with ONE Terminal Cisternae.
one transverse tubule and two terminal cisternae
Triad
Two terminal cisternae and a T-tubule
Triad
The terminal cisternae release calcium ions into the muscle cell in response to an action potential. This calcium triggers muscle contraction by binding to troponin, which allows myosin to bind with actin and initiate the sliding filament mechanism.
A triad in skeletal muscle consists of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum, which are connected functionally and structurally. The T-tubule invaginates into the muscle fiber and facilitates the rapid transmission of action potentials, while the terminal cisternae store calcium ions. When an action potential travels down the T-tubule, it triggers the release of calcium from the terminal cisternae into the cytoplasm, initiating muscle contraction. This close proximity allows for efficient coupling of electrical signals and calcium release necessary for muscle contraction.