Twitch
The phenomenon you are referring to is called the second stimulus before relaxation, which causes increased force, is known as the treppe effect or the staircase phenomenon. This is characterized by the successive increase in muscle contraction force when muscle fibers are stimulated with increasing frequency.
A muscle twitch refers to a single, quick contraction and relaxation of a skeletal muscle in response to an electrical stimulus. In a laboratory setting, researchers can analyze the characteristics of the twitch, such as its duration, force, and the time between the stimulus and contraction (latency). This helps in understanding muscle physiology and the mechanisms of muscle contraction.
The contraction phase refers to the period in muscle physiology where muscle fibers actively shorten, generating tension and force, typically in response to a stimulus. In contrast, the relaxation phase follows this contraction, during which the muscle fibers return to their resting state and lengthen, allowing for recovery and preparation for the next contraction. Understanding these phases is crucial for grasping how muscles function during physical activity.
A subthreshold stimulus is one that does not generate a strong enough signal to elicit a perceptible contraction in muscle fibers. It is below the threshold required to cause an action potential and result in muscle contraction.
The three periods of a myogram, which records muscle contractions, are the latent period, contraction period, and relaxation period. The latent period is the brief time between stimulus application and the onset of muscle contraction. The contraction period follows, during which the muscle fibers actively shorten and generate tension. Finally, the relaxation period occurs as the muscle fibers return to their resting state, allowing the muscle to relax after contraction.
it is known as the threshold stimulus usually seen in tonic contraction
It is only possible to induce an extrasystole during relaxation because the heart needs to be in a certain phase of the cardiac cycle for an extra beat to occur. During relaxation (diastole), the heart muscles are more excitable, making it easier for an extra electrical impulse to trigger a premature contraction. This is why inducing an extrasystole during relaxation is more likely to succeed than during contraction (systole).
The minimum stimulus needed to cause a contraction is called the threshold stimulus. This is the minimal level of stimulation required to activate muscle fibers and initiate a contraction response.
A Muscle Twitch is a single contraction of skeletal muscle. The three distinct phases are latent, contraction, and relaxation. Latent Phase: Is the interval from the stimulus application until the muscle begins to contract (shorten). Note that there is no traced activity during this phase, but there are some electrical and chemical changes taking place during this phase. Contraction Phase: This phase is when the muscle fibers shorten, the tracings will show during this phase (a) peak(s). Relaxation Phase: This phase is represented by the downward curve in your tracings, this is when the muscle is going back to its original state of relaxation and the muscle will once again lengthen
In fact it is not treppe it is wave summation. 4th year bio med! I KNOW MY STUFF!!
The threshold stimulus is the stimulus required to create an action potential. So any stimulus under this level will not cause muscle contraction, while a stimulus above this level will cause the muscle to contract. The higher the stimulus the more muscle fibers are recruited, and thus the higher the response.
Extrasystole is an extra ventricular systole that happens during the begging of relaxation (repolarization). Since the cardiac is able to depolarize only after repolarization, any stimulus upon the repolarization period created an increased ventricular contraction or which is also called extrasystole but not a new contraction.