Skeletal Muscle Lab Report

The protocol and conceptual overview of these procedures can be found under the header, “Properties of Skeletal Muscle” in NPB 101L Physiology Lab Manual Second Edition (Bautista & Korber, 2009, 9-17). The test subject for this lab was the Northern Leopard frog whose spinal cord and brain were severed. In order to carry out the experiments, the materials needed were one medium length surgical scissor, two hemostats and glass dissecting probes, a nine and four inch string, a cup of Ringers saline solution with an eyedropper, and a hook electrode. The software used to analyze and record the data was the BIOPAC system. The procedure starts with the preparation of the frog and the set-up of the equipment. During the remainder of this lab, continuous

The first activity was isolating the gastrocnemius muscle. A cut between the thigh and hip was made so the skin can be pulled down past the lower leg. Then the tendon was cut away from the bone of the heel and one end of the nine-inch string was tied to the tendon. This led to the isolation of the sciatic nerve, found between the hamstring and heel on the lateral side of the thigh. Using fingers, the seams along the quadriceps and hamstring underwent a blunt dissection. In doing so, the glass-dissecting probe was used to free the sciatic nerve embedded in the tissues. A four-inch string was inserted between the nerve and the tissues. Then the transducer was calibrated using a fifty-gram block under the “Frog Muscle” program. Parameter of CAL 1 was changed to zero grams and CAL 2 was changed

Nerve stimulation was induced for every fifteen seconds at an increment frequency of 0.5 pps (parts per seconds), 1.0 pps, 2.0 pps, 4.0 pps, 8.0 pps, 15 pps, and 25 pps. Every increment trial had a thirty-seconds waiting period. To witness the effects of tubocurare on muscle activity, the baseline was maintained between 20-30 grams and a control was established by turning the stimulator on repeat for 60-120 seconds. Then 0.25 ml of tubocurare was infused into the gastrocnemius muscle. The data was recorded for ten minutes.

Last segment in data collection was to analyze the effects of direct electrical stimulation. The hook electrode was disconnected and two electrode needles were inserted about five mm from each end of the gastrocnemius muscle. Starting at the maximum voltage from the first experiment, voltage was slowly increased until a twitch appeared. Then voltage was set ten times the maximum voltage from the first experiment. For both experiments, data were collected for thirty