Question

A myogram is

A. a chart that shows how many muscle cells a neuron synapses with.
B. a recording of the events of a twitch.
C. a measurement of muscle tone.
D. a depiction of the results of a stress test.

Answer 1

A myogram is a graphic record of the electrical activity in a muscle, particularly during a twitch, which includes a latent period, contraction phase, and relaxation phase.

Step-by-step explanation:

A myogram is a graphical recording of the electrical activity that occurs during a muscle contraction, specifically a muscle twitch. When considering the options presented in the question, a myogram relates most closely to choice B, which is a recording of the events of a twitch. A single muscle twitch is characterized by a latent period, a contraction phase, and a relaxation phase:

• During the latent period, the action potential is being propagated along the sarcolemma.
• In the contraction phase, calcium ions (Ca2+) bind to troponin, causing tropomyosin to move from the actin-binding sites, resulting in cross-bridges forming and sarcomeres shortening.
• Finally, during the relaxation phase, tension decreases as calcium ions are pumped back into the sarcoplasmic reticulum (SR) and cross-bridge cycling stops, returning the muscle fibers to their resting state.

Answer 2

A myogram is a graphical recording of the events of a muscle twitch, which comprises a latent period, a contraction phase, and a relaxation phase. Option B is the correct answer.

Step-by-step explanation:

A myogram refers to an instrument that is used to measure twitch tension in muscles. It captures the graphical representation of a muscle twitch, which is a single contraction and relaxation cycle that a muscle fiber goes through when it is stimulated by a nerve impulse.

A twitch consists of three phases - the latent period, where the action potential is being propagated but the muscle has not started contracting; the contraction phase, where the muscle fibers actively shorten and tension increases due to calcium ion interaction with troponin and the shifting of tropomyosin from actin-binding sites, and cross-bridges form; and lastly, the relaxation phase, where tension decreases as calcium ions are pumped back into the sarcoplasmic reticulum and the muscle fiber returns to its resting state.

Therefore, the correct option for what a myogram represents is: B. a recording of the events of a twitch.