The difference between incomplete tetanus and treppe is
A. Treppe allows the muscle to reach a relaxed state briefly between contractions
B. Incomplete tetanus allows the muscle cells to reach a relaxed state briefly between contractions
C. Incomplete tetanus is a constant state of contraction with increased muscle force overtime
D. Both A and B
E. Both A and C
The correct answer and explanation is :
The correct answer is B. Incomplete tetanus allows the muscle cells to reach a relaxed state briefly between contractions.
Explanation:
To understand the difference between incomplete tetanus and treppe, we need to look at how muscle fibers respond to stimulation over time.
- Treppe (also called the staircase effect):
- Treppe is a phenomenon where muscle contractions become stronger with each successive stimulation, but it occurs when each stimulus is delivered after the muscle has relaxed fully (i.e., there is a brief relaxation between stimuli).
- As a result, the muscle gradually generates stronger contractions as the frequency of stimulation increases, but the muscle still relaxes between contractions.
- This can happen when a muscle is subjected to a series of stimuli that are spaced out enough for the muscle to return to a relaxed state after each contraction.
- The effect is due to the fact that there is more calcium available in the sarcoplasm after each stimulus, which leads to increased force generation. This increased availability of calcium enhances the muscle’s contractile response.
- Incomplete Tetanus:
- Incomplete tetanus occurs when the frequency of stimuli is high enough that the muscle does not fully relax between contractions but still experiences partial relaxation.
- The muscle fibers receive rapid stimuli in succession (higher frequency than in treppe), leading to a sustained contraction with brief periods of relaxation.
- This leads to the muscle maintaining a state of partial contraction, and the force generated increases over time as more stimuli are provided, resulting in a higher overall tension.
Key Differences:
- Treppe involves relaxed periods between stimuli, while incomplete tetanus involves minimal relaxation.
- In incomplete tetanus, muscle fibers are continuously stimulated at high frequencies, leading to partial contraction but no complete relaxation, resulting in higher sustained force.
- In treppe, the muscle reaches maximum contraction, but there is a full relaxation between each stimulus.
Thus, the correct choice is B, which highlights that incomplete tetanus allows brief relaxation between contractions, but it does not fully relax like in treppe.