GENERAL HISTOLOGY

Detailed explanation-1: -Without T-tubules, the muscle could not be signaled by the brain to contract, as T-tubules help signal within the cell to contract. T-tubules activate release of calcium from the sarcoplasmic reticulum, which allows for the contraction of muscle fibers by unblocking the F-actin binding site on myosin.

Detailed explanation-2: -T-tubules are invaginations of the plasma membrane, which are present exclusively in striated muscle. Their role is to maintain the SR calcium store under the tight control of membrane depolarization via the voltage sensor channel DHPR [2].

Detailed explanation-3: -The sarcoplasmic reticulum or SR membrane is a membranous network that surrounds the myofibrils and makes contact with the T-tubule at junctions called dyads. So-called “feet” structures join the junctional SR to the T-tubules. These consist of ryanodine receptors (RyR) which form a Ca2+ channel across the SR membrane.