Interactive Links

Watch this videoto learn more about macro- and microstructures of skeletal muscles.

(a) What are the names of the “junction points” between sarcomeres?

(b) What are the names of the “subunits” within the myofibrils that run the length of skeletal muscle fibers?

(d) What gives a skeletal muscle fiber its striated appearance?

Every skeletal muscle fiber is supplied by a motor neuron at the NMJ. Watch this videoto learn more about what happens at the NMJ.

(a) Why is the neurotransmitter acetylcholine degraded after binding to its receptor?

The release of calcium ions initiates muscle contractions. Watch this videoto learn more about the role of calcium.

Watch this video explaining how a muscle contraction is signaled.

(a) What are “T-tubules” and what is their role?

(b) Please describe how actin-binding sites are made available for cross-bridging with myosin heads during contraction.

View this animation of the cross-bridge muscle contraction.