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Fasciculations arise as a result of spontaneous depolarization of a lower motor neuron leading to the synchronous contraction of all the skeletal muscle fibers within a single motor unit. An example of normal spontaneous depolarization is the constant contractions of cardiac muscle, causing the heart to beat. Usually, intentional movement of ...
In concentric contraction, muscle tension is sufficient to overcome the load, and the muscle shortens as it contracts. [8] This occurs when the force generated by the muscle exceeds the load opposing its contraction. During a concentric contraction, a muscle is stimulated to contract according to the sliding filament theory. This occurs ...
Antagonist muscle contraction may serve to prevent injury to joints by preventing the limb from overextending itself and also function to control the distance and time the limb is being moved. Experiments involving ballistic movement of small amplitudes show a marked increase in antagonist muscle activation and experiments where distance moved ...
Once arousal has peaked (1:35), the penis returns to its flaccid state, the scrotum loosens, and the testicles descend. Please note that the arousal/orgasm process can take anywhere from a few seconds to several hours, and this video is intended to demonstrate the typical process, not the typical duration (see an alternate example here).
When necessary, the maximal number of motor units in a muscle can be recruited simultaneously, producing the maximum force of contraction for that muscle, but this cannot last for very long because of the energy requirements to sustain the contraction. To prevent complete muscle fatigue, motor units are generally not all simultaneously active ...
In that study, an increase in muscle fiber conduction velocity was observed when there was a higher level of voluntary muscle contraction, which agrees with the gradual recruitment of higher-force muscle types. [16] In Wistar rats, it was found that cell size is the crucial property in determining neuronal recruitment. [17]
A depiction of a slow wave, contraction and electrical threshold in relation to smooth muscle tone and resting membrane potential.. Gastric slow waves occur at around 3 cycles-per-minute in humans and exhibit significance variances in both amplitudes and propagation velocities in the stomach [8] [9] [10] due to the existence of a gradient of resting membrane potential gradient, [11 ...
Tonic in physiology refers to a physiological response which is slow and may be graded. This term is typically used in opposition to a fast response. For instance, tonic muscles are contrasted by the more typical and much faster twitch muscles, while tonic sensory nerve endings are contrasted to the much faster phasic sensory nerve endings.