Terminal cisternae

Skeletal muscle, with terminal cisterna labeled near bottom.

Terminal cisternae are enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules.

- Terminal cisternae

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Sarcoplasmic reticulum

Membrane-bound structure found within muscle cells that is similar to the smooth endoplasmic reticulum in other cells.

A cartoon section of skeletal muscle, showing T-tubules running deep into the centre of the cell between two terminal cisternae/junctional SR. The thinner projections, running horizontally between two terminal cisternae are the longitudinal sections of the SR.

T-tubules are closely associated with a specific region of the SR, known as the terminal cisternae in skeletal muscle, with a distance of roughly 12 nanometers, separating them.

Skeletal muscle

Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system that are mostly attached by tendons to bones of the skeleton.

A top-down view of skeletal muscle
3D rendering of a skeletal muscle fiber
Muscle types by fiber arrangement
Types of pennate muscle. A – unipennate; B – bipennate; 
C – multipennate
ATPase staining of a muscle cross section. Type II fibers are dark, due to the alkaline pH of the preparation. In this example, the size of the type II fibers is considerably less than the type I fibers due to denervation atrophy.
Structure of muscle fibre showing a sarcomere under electron microscope with schematic explanation.
Diagram of sarcoplasmic reticulum with terminal cisternae and T-tubules.
Human embryo showing somites labelled as primitive segments.
When a sarcomere contracts, the Z lines move closer together, and the I band becomes smaller. The A band stays the same width. At full contraction, the thin and thick filaments overlap.
Contraction in more detail
(a) Some ATP is stored in a resting muscle. As contraction starts, it is used up in seconds. More ATP is generated from creatine phosphate for about 15 seconds. (b) Each glucose molecule produces two ATP and two molecules of pyruvic acid, which can be used in aerobic respiration or converted to lactic acid. If oxygen is not available, pyruvic acid is converted to lactic acid, which may contribute to muscle fatigue. This occurs during strenuous exercise when high amounts of energy are needed but oxygen cannot be sufficiently delivered to muscle. (c) Aerobic respiration is the breakdown of glucose in the presence of oxygen (O2) to produce carbon dioxide, water, and ATP. Approximately 95 percent of the ATP required for resting or moderately active muscles is provided by aerobic respiration, which takes place in mitochondria.
Exercise-induced signaling pathways in skeletal muscle that determine specialized characteristics of slow- and fast-twitch muscle fibers
Jogging is one form of aerobic exercise.
In muscular dystrophy, the affected tissues become disorganized and the concentration of dystrophin (green) is greatly reduced.
Prisoner of war exhibiting muscle loss as a result of malnutrition.

Periodically, it has dilated end sacs known as terminal cisternae.

Triad (anatomy)

Skeletal muscle, showing Triad as well as T-tubule.

In the histology of skeletal muscle, a triad is the structure formed by a T tubule with a sarcoplasmic reticulum (SR) known as the terminal cisterna on either side.

Sarcolemma

Cell membrane of a muscle cell.

Skeletal muscle fiber, with sarcolemma labeled at upper left.

On either side of the transverse tubules are terminal cisternal enlargements of the sarcoplasmic reticulum (termed endoplasmic reticulum in nonmuscle cells).

Diad

Structure in the cardiac myocyte located at the sarcomere Z-line.

General structure of a skeletal muscle cell and neuromuscular junction: 1. Axon

2. Neuromuscular junction

3. Skeletal muscle fiber

4. Myofibril

It is composed of a single t-tubule paired with a terminal cisterna of the sarcoplasmic reticulum.