Question

The "Latent Period" or Lag Phase of a muscle contraction includes all of the events at the neuromuscular junction as well as the "Excitation- Contraction Coupling" mechanisms.

a) True
b) False

Answer 1

The statement is True. The latent period is the time during a muscle contraction when the action potential is being propagated along the sarcolemma and calcium ions are released from the sarcoplasmic reticulum. This phase includes events at the neuromuscular junction and excitation-contraction coupling mechanisms.

Step-by-step explanation:

The statement is True.

The "Latent Period" or "Lag Phase" is the time period in a muscle contraction during which the action potential is being propagated along the sarcolemma (muscle cell membrane) and calcium ions (Ca++) are released from the sarcoplasmic reticulum (SR). This phase includes all the events at the neuromuscular junction as well as the excitation-contraction coupling mechanisms. However, contraction has not yet occurred during this phase.

For example, during an isolated twitch, the action potential triggers the release of calcium ions, which bind to troponin on the actin filaments. This allows the myosin heads to form cross-bridges with actin and initiate the sliding filament mechanism, ultimately leading to muscle contraction.