Incomplete tetanus: is the condition in which stimuli occur so rapidly that there are no intervening relaxations. is the condition in which the muscle fiber only partially relaxes between contractions. results in complete and incomplete tetanus. is the constant tension produced by muscles for long periods of time. is the time during which the tissue cannot respond again.
The Correct Answer and Explanation is:
The correct answer is: is the condition in which the muscle fiber only partially relaxes between contractions.
This answer accurately defines incomplete tetanus, also known as unfused tetanus. To understand why, it is helpful to consider how a muscle responds to nerve stimulation. A single nerve impulse causes a single, brief muscle contraction followed by relaxation, a cycle called a muscle twitch. However, normal muscle movements require more sustained contractions than a single twitch can provide.
This sustained force is achieved by increasing the frequency of nerve stimuli. When a second stimulus arrives before the muscle has fully relaxed from the first, the second contraction builds upon the first, a process called wave summation. As the frequency of stimulation continues to increase, the muscle enters a state of tetanus.
Incomplete tetanus occurs when the stimuli are delivered rapidly, but with enough time between them to allow for very brief periods of partial relaxation. The result is a sustained muscle contraction that is “quivering” or jerky because the muscle tension fluctuates slightly as it partially relaxes and is then stimulated to contract again. This produces more force than a single twitch but is not a completely smooth contraction.
This is distinct from complete tetanus, where the stimulation frequency is so high that there is no time for any relaxation between stimuli. The individual twitches fuse into a single, smooth, sustained contraction at maximum tension. The other options are incorrect: the condition with no intervening relaxations is complete tetanus. The constant tension in resting muscles is muscle tone, and the time when a tissue cannot respond is the refractory period. Therefore, the defining characteristic of incomplete tetanus is the partial relaxation between successive contractions.
