Title: Muscle cell - Wikipedia
Headings: Muscle cell
Muscle cell
Contents
Structure
Microanatomy
Cardiac muscle cells
Myofibrils
Development
Muscle fiber growth
Function
Muscle contraction
Kinds of contraction
Fiber typing
Fiber color
Twitch speed
Type distribution
See also
References
External links

Content: This network is composed of groupings of two dilated end-sacs called terminal cisternae, and a single T-tubule (transverse tubule), which bores through the cell and emerge on the other side; together these three components form the triads that exist within the network of the sarcoplasmic reticulum, in which each T-tubule has two terminal cisternae on each side of it. 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. The sarcolemma was historically synonymous with the cell membrane of a striated muscle fiber or muscle cell. However, there are two other components which form the sarcolemma - basal lamina and reticular fibers. The cell membrane of the sarcolemma receives and conducts stimuli. In skeletal muscle, at the end of each muscle fiber, the outer layer of the sarcolemma combines with tendon fibers. Within the muscle fiber pressed against the sarcolemma are multiple flattened nuclei; embryologically, this multinuclear condition results from multiple myoblasts fusing to produce each muscle fiber, where each myoblast contributes one nucleus. Cardiac muscle cells
The cell membrane of a cardiac muscle fiber has several specialized regions, which may include the intercalated disc, and transverse tubules.