Frog Leg Lab Report

Materials and Methods A frog leg was used for the muscle in the experiments. The skin was removed to expose the gastrocnemius, and the bone was severed just below the achilles tendon. The femur was cut just above the knee, and the tibiofibula was severed just below the knee. Ringer 's solution was applied to the muscle to keep the muscle moist. The procedures were done using a power lab, and a force transducer with a micropositioner. The force transducer was calibrated to give data in Newtons. The force transducer and the electrode leads were attached to the power lab. The force transducer was mounted from the micropositioner, and was positioned above the muscle holder.
Alligator clips from the electrode were attached to the top of the muscle holder to provide the electrical stimulus. The dissected frog leg was then suspended from the force transducer, with the achilles tendon having been tied to a string that was taut and was ran through the transducer. The knee was tied to a muscle holder, firmly in contact to the electrodes, with a second piece of string. The force transducer and muscle holder setup was then connected to the power lab. (ADInstruments

The first hypothesis investigated was that the force of the contraction increases as stretch increases. The muscle was initially positioned so that the string had neither slack nor tension. The muscle was then given a single stimuli of 1.05 V. The stretch of the muscle was increased by raising the micropositioner 1 mm. The muscle was left to rest for 10 seconds, and Ringer 's solution was applied, and the stimulus of 1.05 V was applied again. These steps were repeated until the stretch of the muscle had been increased by 10 mm. The muscle was returned to it’s original position. Each twitch was recorded, with the net force of each twitch being noted. (ADInstruments Lab Tutor ®,