t tubule meaning
n : any of the small tubules which run transversely through a striated muscle fiber and through which electrical impulses are transmitted from the sarcoplasm to the fiber's interior
- In between two terminal cisternae is a tubular infolding called a transverse tubule ( T tubule ).
- In skeletal muscle, the T tubule, an extension of the skeletal muscle plasma membrane, is located here.
- T tubules are the pathways for action potentials to signal the sarcoplasmic reticulum to release calcium, causing a muscle contraction.
- A stimulus, in the form of positively charged current, is transmitted from the neuromuscular junction down the length of the T tubules, activating dihydropyridine receptors ( DHPRs ).
- The sarcoplasmic reticulum serves as reservoir for calcium ions, so when an action potential spreads over the T tubule, it signals the sarcoplasmic reticulum to release calcium ions from the gated membrane channels to stimulate a muscle contraction.