Triad (anatomy)
| Triad | |
|---|---|
 Skeletal muscle, showing Triad as well as T-tubule. | |
 Triad and T-tubule structure and relationship to the sarcoplasmic reticulum in skeletal muscle. | |
| Anatomical terminology |
In the
, which is the smallest unit of a muscle fiber.Triads form the anatomical basis of
dihydropyridine receptors (DHPRs). Their activation causes 1) a negligible influx of calcium and 2) a mechanical interaction with calcium-conducting ryanodine receptors (RyRs) on the adjacent SR membrane. Activation of RyRs causes the release of calcium from the SR, which subsequently initiates a cascade of events leading to muscle contraction
. These muscle contractions are caused by calcium's bonding to troponin and unmasking the binding sites covered by the troponin-tropomyosin complex on the actin myofilament and allowing the myosin cross-bridges to connect with the actin.
See also
- Diad, a homologous structure in cardiac muscle
References
- ^ ISBN 978-0-7817-7057-6.