7 Muscle (Sarcomeres) Flashcards
What is a sarcomere?
The contractile units of muscle - formed by the area between two Z lines in a myofibre. Run along the length of a myofibre like train carriages
What is a Z line?
The end lines of a sarcomere. Anchor thin filaments
What is the I band?
the areas of a sarcomere near the Z lines where there are only thin filaments
What is the A band?
the area of a sarcomere where thick and thin filaments overlap
what is the H zone?
the area of a sarcomere near the middle (M line) where there are only thick filaments
what is the M line?
the centre line of the sarcomere, anchors thick filaments
Describe the triad formed by T tubules and terminal cisternae
located at each end of the sarcomere, at the junction between A and I bands.
T tubules are an extension of the muscle cell sarcolemma into the interior of the myofibre.
Each T tubule has a terminal cisternae running along either side of it, forming a triad.
APs travel along the sarcolemma and along the T tubule, triggering the release of calcium ions from the terminal cisternae into the sarcomeres.
