In this first part, we are going to look at single stimuli on the oscilloscope below. We will begin by clicking 0 volts which should result in a straight line. We will then increase the voltage until we reach threshold for that muscle and a single twitch contraction occurs. Lastly, we will continue to increase voltage to recruited more and more fibers until the all the fibers of that muscle contract. Be sure to scroll down on each page to see the notes Dr. Spock took. At least on the school laptops, the comments are off the page.
The top part of the oscilloscope shows force (y axis) in Newtons over time (x axis) in milliseconds. The bottom is showing when the stimulus occurs. In addition to recording the force in Newtons (top of oscilloscope) you will have to calculate the latent period. That is the period from the stimulus until the contraction occurs.
Click on the voltage on the oscilloscope dial below. Find the latent period and force. (Again, force is give, latent period you have to figure out from reading the screen.) The frog muscle will also not respond at first because the voltage is a subthreshold voltage.
At the end, you will have the option to go onto Part 2 - multiple stimulus to observe treppe and tetanus.