Title: Muscles
Headings: Muscles - Skeletal
Muscles - Skeletal
Chapters
Muscle cells
Skeletal Muscle Contraction
Skeletal muscle (striated muscle)
Neuromuscular junction
Acetylcholine receptor
Striated muscle channels and action potentials
Triads and Sarcoplasmic reticulum
Experiments:
Actin and myosin in muscle contraction
Actin filaments
Myosin thick filament
Sliding filament model
What keeps the thick and thin filaments linked to the Z line?
How does Ca+2 control the interaction between myosin and actin?
Skeletal muscle metabolism

Content: To be effective the whole muscle fiber develops tension at the same time and of course to generate force the muscle fiber is anchored. Muscle fibers contract in response to an electrical signal, depolarization. The signal is generated at the synapse (the neuromuscular junction) and propagated through an action potential via the muscle fiber membrane. The membrane of the cell has specialized invaginations called Transverse-tubules (T-tubules) that enter into the cell (at every 1-2 microns). Thus the action potential can be rapidly transmitted deep into the interior of the cell resulting a delay of only 3-5 msec between the depolarization at the synapse and the first muscle fiber tension. The T-tubule network is so extensive that 50-80% of the plasma membrane is in the T-tubules. Figure 18-31. The sarcoplasmic reticulum (SR) regulates the cytosolic Ca2+ level in skeletal muscle. (a) Three-dimensional drawing of a portion of a muscle cell (myofiber) composed of six myofibrils. The transverse (T) tubules, which are invaginations of the plasma membrane, enter myofibers at the Z disks, where they come in close contact with the terminal cisternae of the SR, forming triads.