Muscle Contraction Lab
Lab 6: Amphibian Muscle Contraction
Results:
For this experiment, Isometric contractions of the gastrocnemius muscle of a frog were analyzed and from this data the latent period, twitch, motor unit summation, tetanus, fatigue & mechanical summation were measured. The data was used to quantify the effect of passive tension on the twitch force, effect of stimulus intensity on the twitch force, effect of stimulus frequency on contractile force of xenopus gastrocnemius muscle.
The threshold voltage obtained was 0.4 volts for the directly stimulated muscle which is higher than the threshold voltage for the directly stimulated nerve, 10 mV. The direct stimulation of the muscle required a higher voltage in order to get a contraction. This most likely occurs for two reasons. First is the fact that once a nerve reaches its threshold voltage, it perpetuates the action potential down the nerve to the muscle. This brings us to the second reason, the nerve branches out and reaches many thousand parts of the muscle, which all get depolarized. When stimulating directly, only the cells surrounding the electrode …show more content…
Both active tension and passive tension are indirectly related by the factor of muscle length. Throughout the run, the length of contracting muscle was controlled by incrementally increasing tension. At 0 mm, the passive tension was 0 g and the active tension was 13.2 g (Excel Spreadsheet C3, D3). At 7 mm, the passive tension was 67.3 g and the active tension was 77.4 g (Excel Spreadsheet C10, D10). As a muscle is stretched, passive tension is generated, a phenomenon comparable to the stretching of a rubber band. The farther apart the ends of the muscle, the farther the muscle can be stretched. Active tension is the tension generated by a muscle in response to electrical stimulation. When the ends of the muscle are farther apart, the muscle achieves maximum tension in response to a stimulus (Linke et al.,
Results:
For this experiment, Isometric contractions of the gastrocnemius muscle of a frog were analyzed and from this data the latent period, twitch, motor unit summation, tetanus, fatigue & mechanical summation were measured. The data was used to quantify the effect of passive tension on the twitch force, effect of stimulus intensity on the twitch force, effect of stimulus frequency on contractile force of xenopus gastrocnemius muscle.
The threshold voltage obtained was 0.4 volts for the directly stimulated muscle which is higher than the threshold voltage for the directly stimulated nerve, 10 mV. The direct stimulation of the muscle required a higher voltage in order to get a contraction. This most likely occurs for two reasons. First is the fact that once a nerve reaches its threshold voltage, it perpetuates the action potential down the nerve to the muscle. This brings us to the second reason, the nerve branches out and reaches many thousand parts of the muscle, which all get depolarized. When stimulating directly, only the cells surrounding the electrode …show more content…
Both active tension and passive tension are indirectly related by the factor of muscle length. Throughout the run, the length of contracting muscle was controlled by incrementally increasing tension. At 0 mm, the passive tension was 0 g and the active tension was 13.2 g (Excel Spreadsheet C3, D3). At 7 mm, the passive tension was 67.3 g and the active tension was 77.4 g (Excel Spreadsheet C10, D10). As a muscle is stretched, passive tension is generated, a phenomenon comparable to the stretching of a rubber band. The farther apart the ends of the muscle, the farther the muscle can be stretched. Active tension is the tension generated by a muscle in response to electrical stimulation. When the ends of the muscle are farther apart, the muscle achieves maximum tension in response to a stimulus (Linke et al.,