Frog Muscle Lab Report

Results A left gastrocnemius muscle of a frog (L=3.2cm in situ) was used in experiment 1 and 2, while a right gastrocnemius muscle of a frog (L=3.4cm in situ) was used in experiment 3. The sciatic nerve of the frog was placed over the stimulatory electrodes covered with a piece of a Kimwipe moistened with Ringer's solution. The relationship between muscle length, force production and velocity of contraction was studied.

Force transduced calibration
In order to get a more accurate data from force transducer, a calibration was made. A series of weight (10-60 grams) was suspended from the "notched" position and the hole position of the blade of a force transducer. Fig 1 shows a positive linear relationship between displacement and load in notch position, and it shows a more positive linear relationship (a steeper slope) between displacement and load in hole position.

Measurement of a single twitch
Fig 2 shows a single twitch of a frog gastrocnemius muscle after a stimulus at 1.0Hz frequency, 10ms duration, and 2.0V intensity. A twitch peak of this single twitch is measure as 58.72g.

Measurement of partial tetany and complete tetany
A partial tetany can be observed when the muscle does not relax completely between stimuli, and a complete tetany can be observed when there is no relaxation between contractions and maximal tension is developed. Fig 3a shows a measurement of partial tetany. With increasing frequency of stimulation, there is less and less time for the muscle fiber to relax between stimuli. Fig 3b shows a measurement of complete tetany. With increasing frequency of stimulation, the contractions eventually fuse, and a smooth powerful tetanus is seen. The peak tetany amplitude is 149.79g, the time to achieve tetany is 0.56s, and the time for relaxation is