Brief Lab Report 1

Brief Lab Report 1 - Steven Pollack Experiments and Results...

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Steven Pollack Brief Lab Report 1 October 11, 2007 Experiments and Results The first three of five exercises were done using the Rana pipiens, otherwise known as the common grass frog. First the frog was cut starting from its thoracic area moving downwards about 4 mm and horizontally in a full rotation around the animal. This allowed for the skin to be removed. The nerve was isolated and extracted from the specimen and placed in a nerve chamber. The nerve was laid out with the stimulating electrode placed on one end of the chamber and the recording electrode 4 cm away vertically completing the necessary circuit. Table 1 shows the data when looking for a threshold, a minimum spike formed by the compound action potential. Table 1 also includes data recorded when the threshold intensity was doubled. Appropriately labeled graphs, 1a and 1b attached to this report include oscilloscope readings depicting the information in Table 1 including extra notations included in the graph as well as in the notes section. Table 1 Intensity (uA) Amplitude (mV) 8.6 7.59 Threshold 17.2 1596.88 2x threshold Table 1 and graphs 1a and 1b represent the biphasic recording. For the second exercise the second of two recording electrodes, R2, was moved to the post in the nerve chamber just past the end of the length of the nerve. The same parameters were measured with this new setup. Table 2 represents the findings. Graphs 2a and 2b represent this data table graphically also through an oscilloscope computer reading. Note graph 2b was measured using the positive black polarity as labeled in the notes for a clearer reading.
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Table 2 Intensity (uA) Amplitude (mV) 10.1 14.38 Threshold 20.2 1470.2 2x threshold Exercise 3 was done by keeping the recording monophasic with the R2 electrode past the nerve. The stimulation intensity was manipulated while the amplitude of the compound action potential was recorded. The positive black polarity was once again used for the oscilloscope reading depicted in Graph 3a. Table 3 reflects the recorded data. Graph 3b graphs that data and shows compound action potential amplitude plotted in an X-Y scatter plot against stimulation intensity. Table 3 Stimulation Intensity (uA) Amplitude (mV) 10.1 14.38 13 206.13 16 1266.18 19 1533.49 22 1541.35 For the last two exercises a new species of frog was used, Rana catesbiana , otherwise known as the American Bull frog. The same dissection was followed as for the first three exercises and the nerve was once again isolated and placed in the nerve chamber. Before any new exercise the threshold was determined as well as the amplitude
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This note was uploaded on 05/18/2008 for the course BIO 335 taught by Professor Cabot during the Fall '08 term at SUNY Stony Brook.

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Brief Lab Report 1 - Steven Pollack Experiments and Results...

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